Tektronix M1000, M2000 Users Guide

M1000/M2000

User Guide

A GREATER MEASURE OF CONFIDENCE

WARRANTY

Hardware

Keithley Instruments, Inc. warrants that, for a period of one (1) year from the date of shipment (3 years for Models 2000, 2001, 2002, 2010 and 2700), the
Keithley Hardware product will be free from defects in materials or workmanship. This warranty will be honored provided the defect has not been caused
by use of the Keithley Hardware not in accordance with the instructions for the product. This warranty shall be null and void upon: (1) any modification of
Keithley Hardware that is made by other than Keithley and not approved in writing by Keithley or (2) operation of the Keithley Hardware outside of the
environmental specifications therefore.

Upon receiving notification of a defect in the Keithley Hardware during the warranty period, Keithley will, at its option, either repair or replace such Keithley Hard­ware. During the first ninety days of the warranty period, Keithley will, at its option, supply the necessary on site labor to return the product to the condition prior to
the notification of a defect. Failure to notify Keithley of a defect during the warranty shall relieve Keithley of its obligations and liabilities under this warranty.

Other Hardware

The portion of the product that is not manufactured by Keithley (Other Hardware) shall not be covered by this warranty, and Keithley shall have no duty of
obligation to enforce any manufacturers' warranties on behalf of the customer. On those other manufacturers’ products that Keithley purchases for resale,
Keithley shall have no duty of obligation to enforce any manufacturers’ warranties on behalf of the customer.

Software

Keithley warrants that for a period of one (1) year from date of shipment, the Keithley produced portion of the software or firmware (Keithley Software) will
conform in all material respects with the published specifications provided such Keithley Software is used on the product for which it is intended and other­wise in accordance with the instructions therefore. Keithley does not warrant that operation of the Keithley Software will be uninterrupted or error-free and/
or that the Keithley Software will be adequate for the customer's intended application and/or use. This warranty shall be null and void upon any modification
of the Keithley Software that is made by other than Keithley and not approved in writing by Keithley.

If Keithley receives notification of a Keithley Software nonconformity that is covered by this warranty during the warranty period, Keithley will review the
conditions described in such notice. Such notice must state the published specification(s) to which the Keithley Software fails to conform and the manner
in which the Keithley Software fails to conform to such published specification(s) with sufficient specificity to permit Keithley to correct such nonconfor­mity. If Keithley determines that the Keithley Software does not conform with the published specifications, Keithley will, at its option, provide either the
programming services necessary to correct such nonconformity or develop a program change to bypass such nonconformity in the Keithley Software.
Failure to notify Keithley of a nonconformity during the warranty shall relieve Keithley of its obligations and liabilities under this warranty.

Other Software

OEM software that is not produced by Keithley (Other Software) shall not be covered by this warranty, and Keithley shall have no duty or obligation to
enforce any OEM's warranties on behalf of the customer.

Other Items

Keithley warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.

Items not Covered under Warranty

This warranty does not apply to fuses, non-rechargeable batteries, damage from battery leakage, or problems arising from normal wear or failure to follow
instructions.

Limitation of Warranty

This warranty does not apply to defects resulting from product modification made by Purchaser without Keithley's express written consent, or by misuse
of any product or part.

Disclaimer of Warranties

EXCEPT FOR THE EXPRESS WARRANTIES ABOVE KEITHLEY DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUD­ING WITHOUT LIMITATION, ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. KEI­THLEY DISCLAIMS ALL WARRANTIES WITH RESPECT TO THE OTHER HARDWARE AND OTHER SOFTWARE.

Limitation of Liability

KEITHLEY INSTRUMENTS SHALL IN NO EVENT, REGARDLESS OF CAUSE, ASSUME RESPONSIBILITY FOR OR BE LIABLE FOR: (1)
ECONOMICAL, INCIDENTAL, CONSEQUENTIAL, INDIRECT, SPECIAL, PUNITIVE OR EXEMPLARY DAMAGES, WHETHER CLAIMED
UNDER CONTRACT, TORT OR ANY OTHER LEGAL THEORY, (2) LOSS OF OR DAMAGE TO THE CUSTOMER'S DATA OR PROGRAM­MING, OR (3) PENALTIES OR PENALTY CLAUSES OF ANY DESCRIPTION OR INDEMNIFICATION OF THE CUSTOMER OR OTHERS FOR
COSTS, DAMAGES, OR EXPENSES RELATED TO THE GOODS OR SERVICES PROVIDED UNDER THIS WARRANTY.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

Sales Offices:BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: [phone]
ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]
JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: [phone]
KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 679 • Fax: [phone]
SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: [phone]
TAIWAN: 1FL., 85 Po Ai Street • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: [phone]

4/02

The

MI

000/M2000

User

Guide

Revision

Copyright

Par1

Number:

A,

-

Keiihley

May

24744

1988

MetraByte

Corp.

1988

Warranty Information

All products manufactured by Keithley MetraByte are warranted against defective materials

and

worksmanship for a period
purchaser. Any product
option
products damaged by improper use.

of

Keithley MetraI3yte.

that

of

one

year from the date

is

found to be defective within

be

repaired

or

replaced.

of

deLivery

the

This

warran@ does

to

the

original

wamty period will, at the

not

apply

Warning

to

Keithleg MetraByte

consequent

designed

to

with

for use

in

the use

components of a level

life

assumes

of

this

support

no

liability

product.

of

or

critical applications.

for

This

reliability suitable

damages

product

is

Disclaimer

Information furnished by Keithley MetraByte
However. the Keithley MetraByte corporation assumes no responsibility for the
information nor
result
rights

from

of

Keithley MetraByte Corporation.

its

for

use.

any

infringements

No

license

is

granted

of

is

believed

patents or other rights

by

implication

to

be

or

otherwise

accurate

of

and

third parties that

under

Notes

Keithley MetraByte/Asyst/DAC
Basicm

IBM@

is

a

trademark

is

a

registered trademark

of

Dartmouth College.

is

also referred

of

International Business Machines Corporation.

to

here-in

as

Kei.Mey

not

reliable.

use

any

patent

MetraByte.

of

may

such

PC,

XT,

AT.

PS/2,

International Business Machines Corporation.

Microsoft@

Turbo

is

C@

is a registered trademark

and

Micro Channel Architecture@

a registered trademark

of

Microsoft corporation.

of

Borland International,

-iv

-

(MCA)

are trademarks

of

New Contact Information

Keithley Instruments, Inc.

28775 Aurora Road

Cleveland, OH 44139

Technical Support: 1-888-KEITHLEY

Monday – Friday 8:00 a.m. to 5:00 p.m (EST)

Fax: [phone]

Visit our website at http://www.keithley.com

Safety Precautions

The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in­struments and accessories would normally be used with non-haz­ardous voltages, there are situations where hazardous conditions
may be present.

This product is intended for use by qualified personnel who recog­nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read and follow all installation,
operation, and maintenance information carefully before using the
product. Refer to the manual for complete product specifications.

If the product is used in a manner not specified, the protection pro­vided by the product may be impaired.

The types of product users are:

Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en­suring that operators are adequately trained.

Operators use the product for its intended function. They must be

trained in electrical safety procedures and proper use of the instru­ment. They must be protected from electric shock and contact with
hazardous live circuits.

Maintenance personnel perform routine procedures on the product

to keep it operating properly, for example, setting the line voltage
or replacing consumable materials. Maintenance procedures are de­scribed in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by
service personnel.

Service personnel are trained to work on live circuits, and perform

safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that
are rated Installation Category I and Installation Category II, as de­scribed in the International Electrotechnical Commission (IEC)
Standard IEC 60664. Most measurement, control, and data I/O sig­nals are Installation Category I and must not be directly connected
to mains voltage or to voltage sources with high transient over-volt­ages. Installation Category II connections require protection for
high transient over-voltages often associated with local AC mains
connections. Assume all measurement, control, and data I/O con­nections are for connection to Category I sources unless otherwise
marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present. A good safety practice is to expect

that hazardous voltage is present in any unknown circuit before
measuring.

Operators of this product must be protected from electric shock at
all times. The responsible body must ensure that operators are pre­vented access and/or insulated from every connection point. In
some cases, connections must be exposed to potential human con­tact. Product operators in these circumstances must be trained to
protect themselves from the risk of electric shock. If the circuit is
capable of operating at or above 1000 volts, no conductive part of

the circuit may be exposed.

Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con­necting sources to switching cards, install protective devices to lim­it fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connect­ed to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.

When installing equipment where access to the main power cord is
restricted, such as rack mounting, a separate main input power dis­connect device must be provided, in close proximity to the equip­ment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jump­ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the com­mon side of the circuit under test or power line (earth) ground. Always
make measurements with dry hands while standing on a dry, insulated
surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip­ment may be impaired.

Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, and as shown on the instrument or test fixture panels, or
switching card.

When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.

Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is ap­plied to the device under test. Safe operation requires the use of a
lid interlock.

5/02

If or is present, connect it to safety earth ground using the
wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should re­fer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or mea­sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.

The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated infor­mation very carefully before performing the indicated procedure.

The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and

all test cables.

To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instru­ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se­lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to in­structions. If the board becomes contaminated and operation is af­fected, the board should be returned to the factory for proper
cleaning/servicing.

MIOQO

SERIES

USERS

R

EMS

The information in this publication has been carefully checked and is believed

to be accurate; however, no responsibility is assumed for possible inaccuracies

or omissions. Applications information in this manual is intended

suggestions for possible use

a

specific application. Specifications may be subject

Ml000

explosive environment unless enclosed in approved explosion-proof housings

MANUAL

I0

N

:

3/30/87

modules are

of

the products and not as explicit performance in

to

not

intrinsically safe devices and should

change

without

not

notice.

be used in an

as

TABLE OF CONTENTS

Warranty

5

CHAPTER1 Getting Started

Default Mode

1-1

Quick Hook-Up 1-2

CHAPTER 2 Functional Description

Block Diagram 2-4

CHAPTER 3 Communications

RS-232C

3-2

Single Module and Multi-party Connection
Software Considerations
Changing Baud Rate 3-5
Using a Daisy-Chain With a Dumb Terminal

RS-485 3-6
RS-485 Multidrop System

CHAPTER 4 Command Set

Table of Commands 4-7
User Commands
Error Messages

4-8

4-1

6

3-3

3-4

3-6

3-7

CHAPTER

5

Setup

Information and Command

Command Syntax 5-2
Setup Hints 5-13

CHAPTER 6 Digital

Digital Outputs
Digital Inputs

110

Function

6-1

6-3

Events Counter 6-4
Alarm Outputs 6-5
On-Off Controller
Setpoi nt

CHAPTER 7 Power

6-9

Supply

CHAPTER 8 Troubleshooting
CHAPTER 9 Calibration
Appendix A ASCII TABLE

Appendix
Appendix
Appendix D

B

M1400

C

M1500

M1600

Data

Sheet
Data Sheet
Data Sheet

6-5

3

WARRANTY

MetraByte Corp. warrants your
parts, materials and workmanship under normal use and service
one year
any defective unit brought to its attention during that period.

MetraByte
be suitable to your purpose.

Some states
ties,

In

no event will MetraByte Corp. be liable to you for any damages, including
profits,
the use or inability to use this product, even
MetraByte
any claim

MetraByte
future patents

Some

consequential damages
you.

so

the

states

from

the date of delivery, and will repair

Corp

makes no implied warranty that the

do

not attow the exclusion of implied warranties or limited warran-

above

lost

savings, or other incidental

dealer

by

Corp.

may not apply to you.

has

been advised

any other party.

cannot assume responsibility for infringement

or

other third party rights resulting from the use of these

do

not allow the limitation or exclusion

so

M1000

the above limitation or exclusion may not apply to

series module

to

be free from defects in

for

or

replace, at its sole option,

M1

000

series modules will

or

consequential damages arising out

if

of

the possibiIity

MetraByte or

of

such damages, or for

of

liability for incidental

an

of

a

authorized

present

products.

period

of

lost

of

or

or

This

except

or

original purchase price.
extend the original warranty period
repaired

warranty is void

by

MetraByte or has been subjected

accident. In no case

or

replaced by MetraByte.

if

the product has been repaired

shall

The

aforementioned provisions

or

altered

to

misuse,

MetraByte's liability exceed

of

any product which has been

negligence,

do

the

not

4

WARNING

The circuits and software contained
are proprietary to MetraByte Corporation. Purchase
products does not transfer any rights
circuits or software used
decompiling

of

the

software program

in

these products. Disassembling or

Reproduction of the software program

As

explained

from

the outside of the

in

the setup section, all setups are performed entirely

M1000

module. There

in

the

MI000

or

grant any license

is

explicitly prohibited.

by

any means is illegal.

is

Series modules

of

these

to

the

no need to open
the module because there are no user-serviceable parts inside.
Removing the cover or tampering with, modifying, or repairing

by

unauthorized personnel will automatically void the warranty.
MetraByte

RETURNS

When returning products for any reason, contact the factory and request

Return Authorization

Authorization Number on

recommends

should not

is

not responsible for any consequential damages.

Number

the

that you insure the product

be

returned collect

and

outside

as

they will

shipping instructions. Write the Return

of

the shipping

for

value

not

be

accepted.

box.

prior

MetraByte

to

shipping. Items

strongly

a

5

CHAPTER

1

GETTING STARTED

Default

AII

Read Only Memory) to store setup information and calibration constants. The
EEPROM replaces the usual array of switches and pots necessary to specify
baud rate, address, parity, etc. The memory is nonvolatile which means that the
information is retained even
never necessary to open the module case.

The
setup parameters may be configured remotely through the communications port

without having to physically change switch and pot settings. There is one minor

drawback in using EEPROM instead

the setup information in the module. It is impossible to tell

module what the baud rate, address, panty and other settings are.
very difficult
baud rate are unknown.
pin labeled DEFAULT
in a known communications setup called Default Mode.

The Default Mode setup is:

Mode

M1000 modules contain an EEPROM ( Electrically Erasable Programmable

if

EEPROM

to

power is removed.

provides tremendous system flexibility since

of

switches; there is no visual indication of

establish communications with a module whose address and

To

overcome this difficulty, each module has an input

*.

By connecting this pin to Ground, the module is placed

300

baud, no parity, any address

No

batteries are used

all

of

just

by

is

recognized.

so

it is

the module's

looking

at the

It

could be

Grounding the

EEPROM. The setup may be read back with the Read Setup
determine all
commands are available

A

module in Default Mode will respond to any address except the four identified
illegal values
command for proper responses. The ASCII value of the module address may
be read back with the
character is to deliberately generate an error message. The error message
outputs the module's address directly after the

Setup information in a module may be changed at
command. Baud rate and parity setups may be changed without affecting the

Default values

the module automatically performs a program reset and configures itself

baud rate and panty stored in the setup information.

The Default
terminal

In most cases, a module in Default Mode may not be used in a string with other
modules.

or

DEFAULT

of

the

(NULL,

of

Mode

computer for the purpose

CR,

300

baud and no parity.

is

intended

pin does not change any of the setups stored in

setups stored in the module. In Default Mode,

as

usual.

$,

#).

A

dummy address must be included in every

RS

command. An easy way to determine the address

to

be used with a single module connected to

(RS)

command

"?

prompt.

will

with the Setup

When

of

identifying and modifying setup values.

the

DEFAULT*

pin is released,

(SU)

to

to

all

the

a

RS-232 &

RS-485

Quick

Hook-Up

Software is not required to begin using your

MlOOO

module.

We

recommend

that you begin to get familiar with the module by setting it up on the bench.

Start by using a dumb terminal
Make the connections shown in the quick hook-up drawings, Figures

Put

the module in the default mode by grounding the Default* terminal. Initialize

the terminal communications package

"terminal" mode. Since this step varies from computer

or

a

computer that acts like a dumb terminal.

on

your computer to put

to

computer, refer to your

1.1

or

it

into the

1.2.

computer manual for instructions.
Begin by typing

$1RD

and pressing the Enter

or

Return key. The module will
respond with an followed by the data reading at the input. The data includes
sign, seven digits and a decimal point.

For

example,

if

you are using

a

thermocouple module and measuring room temperature your reading might be

*+00025.00.

preset

at

to the section

All

modules are shipped from the factory with a setup that includes a channel

address

The temperature reading

will

initially be in

"C

which has been

the factory. Once you have a response from the module

on

commands and get familiar with the command set.

of

1,

300

baud rate,

no

linefeeds, no parity, alarms

off,

you

can turn

no echo

and

2

character delay. Refer to the setup section to configure the module to your

application.

.

1-2

+

10

to

Power

-

Q

1k

41

Figure

+30

Vdc

Supply

+Q

1.1

RS-232C

7

tB

@

8

8

@

-@

8

~B

8

3

Quick

M

VOLTAGE

RS-232C

SIU

Hook-up

1121

0586

i"

RS-485

RS-485

An
evaluation purposes. This connection

and

hook-up. This connection wilI work provided the
current limited to less than
than
requirement. With this connection, characters generated
echoed back.
should

If

the current limiting capability

100R to1

In

some

ground through a 1

Quick

RS-485

should never be

OV.

All

be

turned

ki2

rare cases it may be necessary to connect the

Hook-up

module may be easily interfaced to an

terminals that use

To avoid double characters, the local echo on the terminal

off.

resistor

OOrZ

to

a

RS-232

used

in

series with the

for a permanent installation. Figure

50

to

1

kn

resistor.

ma

1488

of

port

is

and the

and

the

RS-232C

RS-232

only suitable for benchtop operation

RS-232C

1489

output.

RS-232C

receive threshold

style interface IC's

output is uncertain, insert

RS-232C

transmit output is

by

the terminal will be

module's

terminal for

1.3

shows

is

greater

will

satisfy this

DATA

the

a

pin to

+

10

to

Power

+30

Vdc

Supply

Figure

1.3

RS-485

Quick

Hook-Up

with

RS-232C

Port.

1-4

CHAPTER

2

FUNCTIONAL

A

functional diagram of a typical MetraByte sensor module is shown in Figure

2.1

. It is a useful reference designed

and to explain the function
The first step is to acquire the sensor signal and convert it

Figure
the analog-to-digital converter
internally and

The full-scale output

(TS)

the
the unit with a laboratory standard reference applied

The trimmed data now flows into either

performed automatically by the microprocessor after every

filter selection depends on the difference

previous data stored in the output
digit from the

large signal filter is selected.

signal filter is used.

2.1,

all the signal conditioning circuitry has been lumped into one block,

is

transparent

command. The TS command adjusts calibration values stored internally in

EEPROM.

The TS command should only be used to trim the accuracy of

AID

differs from the old output

of

of

many of the modute's commands.

(ND).

to

the user.

the

AID

converter may be trimmed using the Trim Span

If

the change is less than

to

illustrate the data path in the module

Autozero and autocalibration is performed

to

of

two digital filters. The filter selection is
of

the current

data

register.

If

data

by more than

DESCRIPTION

to

digital data. In

the sensor input.

A/D

conversion. The

A/D

output data and the

the least significant decimal

10

counts, the

10

counts, the small

The two-filter system allows for different degrees of filtering depending on the

rate

of

the input change. For steady-state signals, the small-signal filter

averages out noise and

output. The large-signal filter
signals. The time constants for the two filters can

with the Setup

memory. Typically, the srnall-signal filter is set to a larger time constant
large-signal fitter. This gives very good noise rejection along with fast response

to step inputs.

The MetraByte modules allow for user selectable output scaling in
temperature data. This selection is depicted in Figure
the digital filters. The defauk scaling
converted to
position
Setup
temperature applications, the

The scaled data is
obtain the final output value. The output offset is controlled by the user and
serves many useful purposes. The data in the Output Offset Register may be

is

controlled by a bit in the setup

(SU)

(SU)

OF

by feeding the data through a conversion routine. The switch

command. The scaling selection is nonvolatile. For non-

summed

small

is

command.

"c

position should always be selected.

with data stored in the Output Offset Register

input

activated by step changes

changes

The filter values are stored in nonvolatile

to

give a stable steady-state

or

very noisy input

be

specified independently

than

"C

or

2.1

as a switch following

in

the modules

data

and may

is

OC,

but this may be

be

changed with the

"F

the

on

to

used to trim any offsets caused by the input sensor.

undesired signal such

adjust the output to any desired value by loading the appropriate data value in

the offset register. The data in the offset register

as

a tare weight. The

Trim

is

It

may be used to null out

Zero

(TZ)

nonvolatile.

command is used to

The output offset may also be modified using the Set Point

data

loaded into the register. The Set Point command specifies a null value that is
subtracted from the input data. The output reading becomes a deviation value
from the downloaded setpoint. This feature
described in the digital

The value stored in the

(RZ)

sign changed. The output register may
command.

The output data may be read with the Read Data (RD) command. In some
cases when a computer
same data value several times before it

To

(ND)

the New Data Flag is cleared. The flag is set each time the output

is

until the flag

value specified

command. Data loaded in with the

guarantee that the same

command may be used. Each time an RD or ND command is performed,

loaded as the result

is

set before it outputs the data reading.

by

I/O

offset

of

the

SP

section

register may be read back using the Read Zero

is

used

data

a

new

command is multiplied

is

very useful in on-off controllers as

of

this manual.

SP

command will be read back with the

be

reset to zero with the Clear Zero

as

a host,

is

not read more than once, the New Data

A/D

it

may be possible to read back the

is

updated with a new

conversion. The ND command will wait

(SP)

command. The

by

-1

before being

A/D

conversion.

data

(CZ)

register

The remainder of Figure

Digital
general-purpose digital inputs and outputs. These functions are described in
detail in the Digital I/O section.

The heart of the alarm section consists of

high and low alarm limit values. These registers may be down-loaded with data
values by using the HI and
with the same data format that is used with the output data. The high and
alarm registers are nonvolatile
down. The values contained in the alarm registers may be read back at any
time with the Read High (RH) and Read tow (RL) commands.

The

output data. The result

used as control outputs. The high alarm is turned on when the output data

exceeds the high limit value. The low alarm is activated
than the low alarm value. Each alarm has two user selectable modes, either

Momentary

alarm condition is met;

off.

I/O

section. It consist of a versatile alarm function, an event counter and

data

held in the alarm registers

(M)

or Latching

Conversely, when latching alarms are activated, they remain on even

2.1

depicts several functions known collectively

two

registers that are used to store

LO

alarm commands. The alarm values are loaded

so

they

will

not be lost when the unit

is

continually compared with the calculated

of

the comparison is used

(L).

Momentary alarms are activated only while the

if

the output data returns within limits, the alarm is turned

to

trip alarms that may be

if

the output data

as

is

powered

is

less

if

the

low

the

2-2

output data returns within limits. Latching alarms are turned
Alarms (CA) command

or

if

the opposite alarm limit is exceeded.

off

with the Clear

The state

the

alarm outputs may be used to activate digital outputs on the module

connector

the number

are shared with the general purpose digital output bits DO0 and
connect the alarm outputs
used. The connector pins may be switched
outputs using the Disable Alarms

nonvolatile.

The general-purpose digital outputs are open-collector transistor switches that

may be controlled by the host with the Digital Output
designed to activate external solid-state relays to control AC or
circuits. The output may also be
The number
being the maximum.

The Digital Input (DI) command
input pins DIO-D17. The digital inputs are used
other devices. They are also useful
limit switches. The number of digital inputs vanes with the module type.

of

the alarms may be read with the Digital Input

to

turn

on

alarms or to perform simple control functions.

of

terminals required on the module connector, the alarm outputs

to

the connector, the Enable Alarm (EA) command is

back

(DA)

used

of

digital outputs available depends on the module type, with eight

is

used

command. The ENDA selection is

to interface to other logic-level devices.

to

sense the logic levels

to

sense the state

to the general-purpose digital

to

read

(DI)

(DO)

command. They are

logic

of

command. Also,

To

on

levels generated by

electro-mechanical

help limit

D01.

DC

the digital

To

power

The DIO input is shared with the input to the Event Counter. The Event Counter

is

used to accumulate the number

the DWEV connector pin. The counter

(decimal) events and may be read with the Read Events
counter input is filtered and
free input for mechanical switches. The counter value may be zeroed with the
Clear Events

(CE)

command.

uses

of

positive transitions that have occurred on

can

accumulate up

a

Schmitt-trigger input tc provide a bounce-

to

9999999

(RE)

command. The

2-

3

7

W

a

'I

W

0

I

a

a

N

c

L

VI

Y

N

u

II

1

a

t

I

2-4

--%-

w

u

4

..

WP

CHAPTER

3

COMMUNICATIONS

Introduction

The M1000 series of interface modules has been carefully designed to be easy

to

interface to all popular computers and terminals.
from the modules are performed with printable
the information to

languages such as

as

RS-232C, no special machine language software drivers are necessary for
operation. The modules car, also be connected to auto-answer modems for
long-distance operation without the need for a supervisory computer. The

format also makes system debugging easy with a dumb terminal.

be

processed with string functions common

BASIC.

For computers that support standard interfaces such

All

ASCII

communications to and

characters.

This

to

most high-level

allows

ASCII

The MetraByte system

a communications port with a single 4-wire cable.
may

be

strung together on one cable; 124 with repeaters. A practical limit for
232C
communicate with the host on a polling system; that

to

never initiate
protocol must be strictly observed
errors.

Communications to the
command codes such
description
commandresponse sequence would

A

received. The host may not initiate a new command until the response from
previous command
communications collisions. A valid response

units is about ten, although a string of 124 units

its own unique address and must be interrogated by the host. A module can

a

of

all commands is given

Command:

Response:

commandresponse sequence

is

designed to allow multiple modules to be connected to

Up

to

32

RS-485

is

possible. The modules

is,

each module responds

communications sequence.

to

avoid communications collisions and data

Mi

000

modules

as

RD to Read Data from the analog input. A complete

$1

RD

*+00123.00

is

is

complete. Failure to observe this rule will result in

is

in

the Command Set section.

look

like this:

not complete until a vatid response is

can

A

simple command/response

performed with two-character ASCII

be in one of three forms:

modules

RS-

A

typical

a

1)

a normat response indicated by a

2)

an error message indicated by a

3)

a communications time-out error

When a module receives a valid command, it must interpret the command,

perform the desired function, and then communicate the response back
host. Each command has an associated delay time in which the module is busy

calculating the response.

appropriate amount

of

If

the host does not receive a response in an

time specified in Table

'

' * '

'?

prompt

'

prompt

3.1,

to

the

a communications time-out

error has occurred. After the communications time-out it is assumed that

response data is forthcoming. This error usually results when an improper

command prompt or address is transmitted.
The following table lists the timeout specification for each command:

Mnemonic Timeout

DI,

DO,

RD

,WE

ND

All

other commands

10

ms.

See text

100

ms.

no

Table
This timeout specification indicates the turn-around time from the receipt

command to when the module will start to transmit a response.

RS-232C

RS-232C

transfer between computing equipment.

interface to virtually all popular computers without any additional hardware.
Although the
equipment to a computer, the MetraByte system allows for several modules to
be connected in a daisy-chain network structure.

The advantages offered by the

3.1

Response Timeout Specifications.

is

the most widely used communications standard for information

RS-232C

RS-232C

1)

widety used by all computing equipment

2)

no additional interface hardware

3)

separate transmit and receive lines ease debugging

4)

compatible with dumb terminals

standard

RS-232C

is

designed to connect a single piece of

standard are:

in

most cases

versions of the

M1000

of

will

a

However,

1)

2)

3)

4) greater communications delays in multiple-module systems

5) less reliable-loss

6)

7)

3-2

RS-232C

low noise immunity

short usable distance

maximum baud rate - 19200

wiring is slightly more complex than RS-485

host

software must handle echo characters

suffers from several disadvantages:

-

50

to

200

feet

of

one module results in no communications

Single

Module

Connection

Figure
Use the Default Mode to enter the desired address, baud rate, and other setups
(see Setups). The use of echo

the communications line.

Multi-party

RS-232C is not designed to be used in a multiparty system; however the

modules can be daisychained to allow many modules to be connected to
single communications port. The wiring necessary to create the daisy-chain
shown in Figure 3.1. Notice that starting with the host, each Transmit output
wired
sequence must be followed until the output of the last module in the chain is
wired to the Receive input of the host.
the same baud rate and must echo ail received data (see Setups). Each module

must be setup with its own unique address

(see Setups). In this network, any characters transmitted by the host are

received by each module

information
the commands given by the host are examined by every module.
the chain

by transmitting the response

be ripple through any other modules

destination, the Receive input of the host.

1.1

shows the connections necessary to attach one module

is

not necessary when using a single

Connection

to

the Receive input

is

echoed back

is

correctly addressed and receives a valid command, it will respond

of

the next module in the daisy chain. This wiring

All

modules in the chain must be setup to

to

avoid communications collisions

in

the chain and passed on to the next station until the

to

the Receive input

on

the daisy chain network.

in

the chain until it reaches its final

of

the host. In this manner all

The

to

module

If a module in

response

a

host.

Ml000

data

on

a

is

is

will

The daisy chain network must be carefully implemented to avoid the pitfalls

inherent in its structure. The daisy-chain is a series-connected structure and any

break in the communications link will bring down the whole system. Several

rules must be observed

1.

All

wiring connections must be secure; any break in the wiring, power,
ground, or communications will break the chain.
plugged into their respective connectors.

2.

All

modules must be setup for the same baud rate.

3.

All

modules must be setup for echo.

to

create a working chain:

All

modules must be

3-3

I

+10

+30Vdc

to

RS-232

+

-

To

+Vs

Figure

Software

If

the host device
messages on its Receive input along with the responses from the module. This
can usually be handled by software string functions by observing that a module
response always begins with a
return.

A

properly addressed

characters

receiving the carriage return, the module will immediately calculate and transmit
the response
characters that appear on its receive input. However,
during this computation period, it will
buffer.

the

module. This situation will occur

character on the command carriage return. In this case the linefeed character
will be echoed after the response string has been transmitted.

Considerations

in

the command including the terminating carriage return. Upon

to

This

character will be echoed after the response string is transmitted

3.1.

RS-232

is

a

computer, it must be able to handle the echoed command

MI000

the command. During this time, the module will not echo any

Da

sy

Chain

' * '

or

' ? '

module in a daisy chain will

be

stored in the module's internal receive

if

the host computer appends a linefeed

Network

character and ends with a carriage

if

a

character is received

echo

all of the

by

The daisy chain also affects the command timeout specifications. When a

module in the chain receives a character
character through the module's internal UART. This method

more reliable communications since the UART eliminates any slewing errors
caused

3-4

by

the transmission lines. However, this method creates a delay in

it

is echoed by retransmitting the

is

used

to

provide

propagating the character through the chain. The delay

necessary to retransmit one character using the baud rate setup in the module:

is

equal to the time

Baud Rate
300 33.30 ms.

600

1200 8.33
2400
4800

9600

One delay time is accumulated for each module in the chain.
four modules are used in a chain operating at
delay time is 4 X

listed in Table

For

modules with RS-232C outputs, the programmed communications delay

specified in

NULL character
This results in a delay
specified in the setup data, this sequence is repeated. Programmed
communications delay
each module in the chain

the

8.33

3.1

to calculate the correct communications time-out error.

setup data (see Setup section)

(00)

Delay

16.70

ms.

ms.

4.1

7

ms.

2.08

ms.

1.04

ms.

For

example,

1200

ms.

=

33.3

ms.

This

time must be added to the times

is

followed by an

of

two character periods.

is

seldom necessary in an RS-232C daisy chain since

adds

one character of communications delay.

idle

line condition for

baud, the accumulated

implemented by sending

one

character time.

For

longer delay times

if

a

Changing

It

is possible to change the baud rate of an RS-232C daisy chain on-line. This

process must be done carefully

module

reset can be caused by the Remote Reset
power interruptions.

using the Read Setup
for the same baud rate.

power to the modules. This generates a power-up reset in each module and

loads in the new baud rate.

com m u nications.

8aud

1.

Use the Setup

in

the chain. Be careful not to generate a reset during this process.

2. Verify that

3.

Remove power from

4. Change the host

Rate

to

avoid breaking the communications link.

(SU)

command

all

the modules in the chain contain the new baud rate setup

(RS)

command. Every module in the chain must be setup

all

the modules for

baud

to

change the

(RR)

at

rate to the

bmd

command, a line break,

least

new

rate setup

10

seconds. Restore

value

and

on

each

check

A

or

5.

Be sure to compensate

of

the new baud rate.

for

a

different communications

delay

as

a result

~~

Using A Daisy-Chain

A dumb terminal can be used to communicate to a daisy-chained system. The
terminal is connected in the same manner
Any commands typed into the dumb terminal will be echoed by the daisy chain.

To

avoid double characters when typing commands,
duplex mode or turn
command echo.

RS-485

RS-485
multidropped systems that can communicate
distances. RS-485
of wires switching from

handle common mode voltages from
them ideal for transmission over great distances. RS-485 differs from RS-422
using one balanced pair of wires

RS-485 system cannot transmit and receive at the same time it is inherently a

half-duplex system.

is

a

recently developed communications standard to satisfy the need for

With

off

is

similar to RS-422 in that

A

Dumb

the

local

0

to

5 volts to communicate

Terminal

echo. The daisy chain will provide the input

-7V

for

both transmitting and receiving. Since an

as

when using a computer as a host.

set

the terminal

at

high data rates over long

it

uses a balanced differential pair

to

+12V

data.

without

RS-485 receivers can

loss

of

data, making

to

full

by

RS-485 offers many advantages over

1)

balanced line gives excellent noise immunity

2)

can

be

used

to

to

communicate with

3)

communications distances up

4) true multidrop; modules are connected in parallel

5)

modules can be disconnected without breaking communications

6)

up to

32

modules

7)

no

communications delay due to multiple modules

8) simplified wiring using standard telephone

Of course, RS-485 does have its disadvantages. Very few computers or
terminals have built-in support for
available
become available
system usually requires the extra expense

Metra8yte

RS-485.For systems that require more than
distances,

for

the

IBM

as

Cop.

or

offers interface converters to convert RS-232C and

high speed, RS-485

on

one

PC

and compatibles and other RS-485 equipment will

the standard gains popularity. This means that an

RS-232C:

M1

000 modules at 38400 baud

to

10,000

line; 124 with repeaters

feet.

cable

this

new standard. Interface boards are

of

an interface.

a

few modules, long wiring

is

recommended

RS-485

RS-422

to

3-6

Host

RS-485

..

-

DO(G)

GNDlB>

T

B=

Black

R=

Red

G=

Green

v=

Yellow

up

ra

10,000

Feet

+

Figure

3.2.

RS-485

MuItidrop Network.

I

RS-485

Figure
Notice that every module has a direct connection
number
remaining modules. Each module must be setup with a unique address and the
addresses can be

to

module are labelled with notations
designate the

This color convention

installation.
match the labeled pins with the wire cotor

Multidrop

3.2

illustrates the wiring required for multiple-module

of

modules may be unplugged without affecting the operation of the

avoid bus conflicts (see Setup). Also note that

colors

Label Color

(6)

GND

(R)

v+

(G)

DATA* Green

(Y)

DATA Yellow

If

System

in

any order.

used on standard 4-wire telephone cable:

Black

Red

is

used on all MetraByte

standard 4-wire telephone cable

All

RS-485

(B),

(R),

to

guarantee correct installation.

modules

(G),

RS-485

is

to

must

the

and

used,

RS-485

the host system. Any

be setup for no echo

connector

(Y).

equipment to simplify

it

is only necessary

pins

These notaticns

system.

on each

to

The notation

of DATA (negative true).

To minimize unwanted reflections

arranged
structures

500

feet total, the end

connected between DATA and DATA*.

as

of

'

'

on the label DATA* is simply used to indicate the complement

on

a

line going from one module

the

transmission line should be avoided. For wire

of

the

line

should

the transmission line, the

to

the next. 'Tree'

runs

be terminated with

a

100

bus

should be

or

random

greater than

ohm resistor

3-7

Special care must be taken with very long busses (greater than

ensure error-free operation. Long busses must be terminated as described

above. The use of twisted cable for the DATA and DATA* lines will greatly

enhance signal fidelity. Use parity and checksums along with the

commands to detect transmission errors. In situations where many modules are

used on a long line, voltage drops in the power leads becomes an important

consideration. The

common reference for the transmission line receivers in the modules. Voltage

drops in the
The receivers are rated

reliable operation, the common mode voltage should be kept below -5V. The

resistance of

ohms per

Using Ohm's Law, the maximum allowable resistance in the
within the -5V. common-mode condition is

results
calculations can be reduced to a general rule-of-thumb by taking the number

modules on the bus and multiplying it by the
number must be less than the number given in the following Table

in

Wire Gauge Maximum modules X feet

GND

20

1000

a maximum bus length

GND

leads appear

gauge wire commonly used

feet. The maximum current

wire is used both as a power connection and the

as

a

common-mode voltage to the receivers.

for a maximum

of

of

6670 feet for a single module. These

-7V.

draw

66.7

bus

of common-mode voltage. For

in

telephone cable is about

from a single module is 75 ma.

ohms. For

length in feet.

20

1000

'#'

GND

gauge wire this

The

:

feet) to

form of

lead to be

resultant

all

10

of

22

20

18
Communications
All

M1000

units of communications delay after a commacb has bee:: received (see
section). This delay is necessary when using host computers that transmit
carriage return as a carriage return-linefeed string. Without the delay, the

linefeed character may collide with the first transmitted character from the
module, resulting in garbled data.
return as a single character, the delay may be set to zero to improve

communications response time.

modules with RS-485 outputs are setup at the factory to provide two

Delay

4000

6000

i

0000

If

the

host

computer transmits a carriage

Setup

a

CHAPTER

4

COMMAND

The

M1000

control all module functions. A command must be transmitted to the module by
the host computer

A

module can never initiate a communications sequence.

mands exists to exploit the full functionality

commands and a sample format for each command is listed in Table

Command

Each command message from the host must begin with a command prompt
character to signal to the modules that a command message is to
are two valid prompt characters; a dollar sign character
short response message from the module.
amount of data necessary
character is the pound sign character

long

response format will be covered a little later).

The prompt character must be followed by
identifying the module to which the command is directed. Each module
attached to a common communications
address
addresses are assigned by the user with the Setup
resub, use printable

$41)

are the best choices for address characters.

modules operate with

or

terminal before the module will respond with useful data.

Structure

to

complete the command. The second prompt

so

that commands may be directed to the proper unit. Module

ASCII

characters such as

a

simple commandhesponse protocol to

A

variety of com-

of

the modutes.

($)

A

short response is the minimum

(#)

which generates long responses (the

a

single address character

port

must be setup with its own unique

(SU)

'1'

(ASCII

A

list of available

4.1.

follow.

is used to generate a

command. For best

$31)

or

'A'

SET

There

(ASCII

The address character is followed

the function to be performed by the module.

listed in Table
described in full later in this section. Commands must be transmitted as upper­case characters.

A

two-character checksum

user option. See 'Checksum' section below.

All

commands must be terminated
(In all command examples in this text the Carriage Return is either implied
denoted by the symbol

Data

Structure

Many commands require additional data values to complete the command

definition as shown in the example commands

necessary

descriptions.

4.1

along with a shcrt

may

'CR'.)

for

these commands is described

by

a

two-character command which identifies

All

of

the available commands are

function definition.

be appended to

by

a Carriage Return character

in

in

any

command message as a

Table

full

in

All

commands are

(ASCII

4.1.

The particular data

the cornpIete command

$OD).

OF

The most common type
data. Analog data is always represented in the same format for
the

MlOOO

consisting of a sign, five digits, decimal point, and two additional digits. The
string represents a decimal value in engineering units.

series. Analog data is represented as a nine-character string

Examples:

of

data used in commands and responses is analog

all

models in

-1-1

2345.68

+00100.00

-00072.1

0

-00000.00

When using commands that require analog data as an argument, the full nine­character string must be specified, even though some digits may not be
significant. Failure

Analog data responses from the module will always be transmitted in the nine­character format. This greatly simplifies software parsing routines since all

analog

data

is

to

do this

in the same format for

will

result in a SYNTAX

all

module types.

ERROR.

In many cases, some
instance,
resolution.

-1-00123.00

nificance in this particular model. However, the data format

to in order to maintain compatabitity with other module types.
The maximum computational resolution of the rnodute is

than the resolution that may be represented by an analog data variable. This

may lead to round-off errors in
be sto:ed in a

Command:

the

M1300

A

typical analog data value from this type of module could be

. The two digits to the right of the decimal point have no sig-

M1

OCO

$1

of

the digits in the analog data may not be significant. For

thermocouple input modules feature 1 degree output

is

always adhered

16

bits, which

some

module using the 'HI' arnmand:

HI+i2345.67M

cases. For example, an alarm value may

is

less

Response:

The alarm value may then

Command:

Response:

It appears that the data read back does not match the value that
saved. The error is caused by the fact that the value saved exceeds
computational resolution of the module.
appears when large data values saved in the module's

In

most practical applications, the problem is nonexistent.

$1

RH

*+12345.60M

be

read

back

with the Read High

This type of round-off error only

(RH)

command:

EEPROM

was

originally

the

are read back.

Overload values of analog data are represented by 49999.99 and -99999.99

4-2

-

Data read back from the Event Counter with the Read Events

in the form of a seven-digit decimal number with no sign or decimal point.

Round-off errors do not occur on the event counter.

For example:

(RE)

command

is

Command:
Response:

The Digital Input, Digital Output, and Setup commands use hexadecimal

representations

the command descriptions.

$1

RE

'0000123

of

data. The data structures for these commands are detailed in

Write Protection

Many of the commands listed in Table

Protected Commands'. These commands are used

module's
idental
Write Enable

Miscellaneous

The address character must transmitted immediately after the command prompt
character. After the address character the module

below

$20)

EEPROM.

loss

of setup data.

(WE)

ASCII

within the command message for better readability

$23

These commands are write protected to

All

write-protected commands must be preceded by a

command before the protected command may be executed.

Protocol

(except,

Notes

of

course,

CR).

are under the heading of 'Write

4.1

to

alter setup data in the

This

allows

if

guard

will

ignore any character

the

use

desired.

against

of

spaces (ASCII

acc-

The length
properly addressed module receives a command message
characters the module will abort the whole command sequence and

response will result.

If

a

properly addressed module receives a second command prompt before

receives

Response

Response messages from the
(ASCII
indicates acknowledgment of a valid command. The
error message.
commands simply return a single
command
information following the
may be found in the detailed command description.

The maximum response

of

a

CR,

Structure

$2A)

has

a

command message is limited to

the command will be aborted

M1000

or a question mark

All

response messages are terminated

been executed by the module. Other commands send data

' * '

message

'

?

prompt. The response format of

length is

and

module begin with either an asterisk

'

(ASCII

'

'

character to

20

characters.

20

printable characters.

of

more than

no response will result.

$3F)

prompt. The

'

?

'

prompt precedes an

with

a

acknowledge

all

' '

prompt

CR.

that the

commands

Many

if

a

20

no

it

' '

4-3

A

commandhesponse sequence is not complete until a valid response is

received. The host may not initiate a new command until the response from a
previous command is complete. Failure to observe this rule will result in
communications collisions. A vaIid response can be in one

1)

a

normal response indicated

2)

an error message indicated by

3)

a communications time-out error

by

a

a

'

'

'

?

'

prompt

prompt

of

three forms:

When a module receives a valid command,

perform the desired function, and the communicate the response back

host. Each command has an associated delay time in which the module is busy
calculating the response.
appropriate amount of time specified in Table
error has occured.

response data is forthcoming. This error usually results when
command prompt

Long Form Responses

When the pound sign
with a 'long form' response. This type of response

message, supply the necessary response data, and will
checksum to the end
where the host wishes to verify the command received by the module. The
checksum
command prompt may be used with any command. For example:

Command:
Response:

is

included

After

or

address

' # '

of

to

$1

RD

*+00072.10

If

the host does not receive a response

the communications time-out it

is

transmitted.

command prompt

fhe message. Long form responses are used in cases

verify the integrity

(short

it

must interpret the command,

4.1,

a communications time-out

is

assumed

is

used, the module will respond

will

echo the command

add

a

two-character

of

the response data. The

form)

an

improper

that

fo

in

'

the

an

no

#

'

Command:

Response:

#I

RD

'1

RD+00072.1

(long

OA4

(A4shecksum)

form)

Checksum

Checksum, a two character hexadecimal value added to the end
verifies that the message received
The checksum ensures the integrity

Command Checksum

A

two-character checksum may be appended to any command

module
two extra characters and assumes that

present, the module will perform the command normally.
characters are present, the module

as

a user option. When a module interprets a command, it

is

exactly the same as the message sent.

of

the information communicated.

it

is a checksum.

will

calculate the checksum for the

If

the checksum

If

4-4

of

a

to

looks

the

the

message,

M1000

for the

is

not

two

extra

message.

checksum, the module will respond with a 'BAD

and the command

be executed.

a

'SYNTAX

If

the calculated checksum

will

be aborted.

If

the module receives a single extra character,

ERROR'

and

the command will be

does

If

the checksums agree, the command will

not agree with the transmitted

aborted.

CHECKSUM' error message

it

will

respond with

For

example:

Command: $1 RD
Response: *+00072.10

Command:
Response: *+00072.10

Command:
Response:

Command:

Response: ?I

Response Checksums

If

the long form

checksum

Command:
Response: *+00072.10

Command:
Response:

will

$1

RDEB

$1

RDAB (incorrect checksum)

?I

BAD

$1

RDE

SYNTAX

'

#

'

be appended to the end

$1

RD

#I

RD

*I

RD+00072.1OA4 (A4=checksum)

CHECKSUM

(one extra character)

ERROR

version

of

(no

checksum)

(with

checksum)

a

command

of

the response. For example:

(short

(long form)

is

form)

transmitted to a module, a

Checksum Calculation

The

checksum is calculated
ASCII characters
are used as the checksum. These two digits are then converted to their
character equivalents and appended to the message. This ensures that the
checksum is in the form

Example: Append a checksum

Characters:

ASCII

Sum

The checksum

of

the message: #1

hexvalues:

(hex

in

the message. The lowest order two hex digits

addition)

is

73

of

#1

23

(hex).

DOFF73

by

summing the hexadecimal values

printable characters.

to

the command

DOFF

44

4F

31

23

+

31

Append the characters 7 and

46 46

+

44 + 4F + 46

#I

+

DOFF

46

=

173

of

all

of

the sum

ASCII

3

to the end

the

4-5

Example: Verify the checksum

of a module response

*1

RD+00072.1

OA4

The checksum is the
Add the remaining character vafues:

two

characters preceding the

CR:

A4

*lRD+OOO72.

2A+

31

+

52+

44+

2B+

30+

30+

30+

37+

32+

2E+

31+

The two lowest-order

transmitted checksum.

Note
calculated hex integer. The variables must
software to determine equivalency.

If

If

included in the checksum calculation.

Panty bits are never included in the checksum calculation.

that

the transmitted checksum is the character string equivalent to the

checksums do not agree, a communications error has occurred.

a

module

is

setup to provide linefeeds, the linefeed characters are not

hex

digits

of

the sum are

be

A4

which agrees with the

converted to like types in the host

10

30

=

2A4

4-6

Table

4.1

MlOOO

Command

Set

Command and Definition

DI

DO

ND
RD
RE

RL

RH
RS

Rz

WE

Write Protected Commands.

CA

CE

cz

DA

€A

H1

LO

RR

su

SP
TS

Tz

Read AlarmdDigital Inputs
Set Digital Outputs
New Data
Read Data
Read Event Counter
Read
Read
Read Setup
Read

Write

Low

Alarm Value

High

Alarm Value

Zero

Enable

Clear Alarms

Clear

Clear Zero
Disable
Enable
Set High Alarm Limit
Set
Remote Reset

Setup

Set Setpoint

Trim Span
Trim Zero

Events

Alarms

Alarms

Low

Alarm Limit

Module

Typical

Command

Message

($

prompt)

$1

DI

$1

DOFF

$1

ND

$1

RD

$1

RE

$1

RL

$1

RH

$1

RS

$1

Rz

$1

WE

$1

CA

$1

CE

$1

cz

$1

DA

$1

EA

$1

HI+I

2345.67L

$1 L0+12345.671_

$1

RR

$1

SU31070l42

$1

SP+00600.00

$1

TS+00600.00

$1

Tz+ooooo.oo

Typical

Response

Message

*0003

*

*+00072.00

*+00072.00

*0000107

*+ooooo.oo

*+00510.00

*31070142

L

L

*+ooooo.oo

*

*

rc

*

t

*

*

*

*

4-7

MI000

User Commands

Note that in
return is implied after every character string.

all

command and response examples given below, a carriage

Clear Alarms (CA)

The clear alarms command turns both the
mand does not affect the enable/disable or momentary/latching alarm con­ditions. The alarms will continue to be compared
command is given. In cases where the alarm condition persists, the alarms

be

set at the end

CA

command is

information.

Command:
Response:

Command:

Response:

of

the next input data conversion. The primary purpose

to

clear latching alarms.

$1

CA

*

#I

CA

*1

CADF

HI

See

and

LO

alarms

to

the input data after

the Alarms section

OFF.

This com-

the

GA

will

of

the

for

more

Clear Events (CE)

The Clear Events ccmmand clears the events counter to

Command:

Response:
Command:

Response:

Note:
mand must be sent to resume counting.

Clear

The
This command clears any data resulting from a Trim Zero
command.

When the events counter reaches

Zero

Clear

Command:

$1

CE

*

#1

*lCEE3

9999999,

(CZ)

Zero

command clears the output offset register value to

$1CZ

0000000.

it stops counting.

Response:
Command:

Response:

#1

CZ

*1

CZF8

(TZ)

A

CE

+OOOOO.OO.

or

SetPoint

com-

(SP)

4-

8

Disable Alarms (DA)

Most models in the MlOOO series feature LO/DOO and

module connector. These pins serve a dual function and can be used
either the alarm outputs or digital outputs 0 and
command
The alarm settings are not affected in any

is

used

to

connect the digital outputs 0 and 1 to the connector pins.

way

except that the alarm outputs are
disconnected from the module connector. The alarm status can
with the Digital Input

Enable Alarms

(EA)

Command:

Response:
Command:

Response:

Digital Input

The

DI

command reads the status

ponse to the

(DI)

DI

(DI)

command.

$1

DA

*

#1

DA

*I

DAEO

command

command. The complement

of

the digital inputs and the alarms. The res-

is

four hex characters representing two

HI/D01

1. The Disable Alarms

to

the

DA

pins on the

to

output

still

be read

command is the

bytes

of data.
The first byte contains the alarm status. The second byte contains the digital
input

data.

Command:

Response:

Command:

Response:

$1

DI

*0003

#I

DI

*I

D10003AB

Listed below are the four possible alarm states in the first digital input byte and

their hex

00

01

02

03

The second byte displays the hex value

values.

Both

HI

alarm

HI

alarm

Both

HI

HI

and

off.
on.

and

LO

alarms

LO

alarm on.

LO

alarm

LO

alarms on.

off.

off.

of

the digital input status. The number

of digital inputs vanes depending on module type.

Diaital - InDuts
Data

Bits

For example: A typical response from a
response indicates
other digital inputs are

017

D16

D15

D14

D13

D12

DI1

DlQ

76543210

$1

DI

command could be:

that

the

HI

=

alarm

1.

is

off, the

LO

alarm

is

on,

'01

DIO

=

FE.

0

This

and

all

4-9

~~

All

digital inputs that are not implemented or left unconnected are read as

~

'1'.

Digital input 0 serves a dual function.

It

is both a digital input and the Event

Counter input.
When

reading digital inputs with a checksum, be sure not to confuse the

checksum with the data.

Digital

The

Output

DO

command controk eight bits of digifai outputs on the module connector.

(DO)

The number of digital outputs implemented depends on the model used. The
digital outputs
command. The DO command requires an argument
specifying the eight bits

Diaital - OutDuts

Data Bits

The electrical implementation

transistors wired to the module connector. If a digital output

corresponding transistor
output
to

bit

is set to

'0'

the corresponding transistor

allow

the module to control external circuits under host

of

output data.

DO7

'1'

DO6

7

is

DO5

6

of

DO4

5

003

4

the digital output consists of open-collector

turned on and sinks current. Note that when a digital

the electrical output is near 0 volts.

is

turned

off

and sinks no current.

3

DO2

2

of

two hex characters

DO1

DO0

If

1

a

0

is

set

to

digital output is set

'1'

the

Assume a module has two digital outputs, and you wish
(sinking current). Set
two digital outputs,

data

bit 0 and data bit 1 to

at1

the other bits are 'don't cares'. For example, this

'1'.

Since the module has

command will turn both outputs 'on':

Command:

$1

DOFF

Response:

To

turn both outputs

Command:

$1

DO00

off

you could use the command:

Response:

Digital outputs 0 and 1 share connector pins with the
Disable

Alarms (DA) command

is

used

to

configure these pins

outputs.
Digital output settings are not stored

occurs,

The

software provision

all

digital outputs will be

DO

command is the

to

set

only

means

read the state

in

nonvolatile memory.

to 0 upon power up.

of

changing digital outputs. There

of

the digital outputs.

to

turn both outputs

HI

and

LO

alarms. The

If

a

power failure

as

on

only

digital

is

no

4-

10

Enable

Alarms

(EA)

Digital outputs DOO/LO and

alarms. Digital output 0 is shared with the
shared with the
shared outputs to indicate alarm conditions and disconnects digital outputs 0 and

I.

The

EA

The alarm status can be read at any time with the Digital Input (DI) command.
The complement

Command:

Response:

Command:

Response:

High

The high alarm command sets the value and type
specified by the

sensor data after every
is greater than the value stored by the

read using the Digital Input
digital output by using the Enable Alarms (EA) command. The
specifies whether the high alarm
alarm type,
example:

Alarm Limit

HI

alarm. The Enable Alarms (EA) command configures the

command only affects the electrical output of the alarms to the pins.

to

the

$1

EA

*

#1

EA

*I

EAEI

(HI)

HI

command is stored in nonvolatile memory and compared with the

"L"

for latching or

DOl/HI

EA

command is the Disable Alarms (DA) command.

A/D

conversion. The high alarm is activated

(DI)

"M"

serve a dual purpose as digital outputs and

LO

alarm and digital output 1 is

of

the high alarm.

HI

command. The high alarm status may be

command. The alarm may

is

momentary

for momentary, must

or

latching. A letter indicating the

follow

be

used

HI

the alarm value.

The data

if

the input data

to

activate

command also

a

For

Command:

Response:

Command:

Response:

The alarm limit

is

set beyond the output range, the alarm will be activated

condition.

The high alarm value may be read back with the

A latched alarm may be cleared with the Clear Alarms
information on alarms may be found in the Digital

$1

*

#I

'1

should

H1+00100.00M

H1+00100.00M

HI+00100.00ME3

be set within the output range

Read

I/O

of

the module.

High Alarm

section.

If

the alarm limit

only

on an overload

(RH)

(CA)

command. More

command.

4-11

Low

Alarm Limit (LO)

The low alarm command sets the value and type
with the LO command is stored in nonvolatile memory and compared with the sensor

data after every A/D conversion. If the input data is less than the low limit, the low
alarm is activated. The low alarm status may be read using the Digital Input

command. The alarm may be used to activate a digital output by using the Enable
Alarms (EA) command. A letter indicating the alarm type,

momentary, must follow the alarm value. For example:

Command:

Response:

Command:

Response:

The alarm limit should be set within the output range of the module. If the alarm limit

is

set beyond the output range, the alarm will be activated only on an overload

co ndi tio n
The low limit value may be read back with the Read Low Limit (RL) command.

More information on alarms may be found in the Digital

.

$1

LO+OOOOO.OOM

*

#I

LO+OOOOO.OOM

*I

LO+OOOOO.OOMEC

of

the low alarm. The dataspecified

"L"

for

latching or"M"for

I/O

section.

(DI)

New

Data Command

The

New

Data (ND) command is avariation of the Read Data (RD) command used

to read sensor data from the module. The ND command guarantees that the output

data has not been previously read.
The

M1000

result
reads the resuits stored in the output buffer. A fast

baud rate could possibly read the output buffer several times before the information
is updated with a new A/D conversion. This results in redundant information which

may be confusing or may be a waste
Associated with the output buffer is the New Data Flag (see Figure

is cleared each time an RD or ND command is performed. The flag is set when the
module's microprocessor loads the output buffer with the result of the most recent

A/D conversion. The ND command will output data only when the New Data Flag

is set.
until new data

Thus, the output data obtained with an ND command is always the result of a new
AID conversion.

in

module acquires analog input data eight times a second and stores the

the output buffer (see Figure

If

the flag is cleared when an ND command

is

(ND)

2.1). The

of

host processor time.

present in the output buffer before responding to the command.

Read Data (RD) command simply

host

communicating at a high

2.1).

is

received, the module will wait

This flag

4-12

The ND command is especially useful with computers that handte communications

on

an interrupt basis. The ND command may be used to get the maximum possible

throughput without producing redundant data.

$1

Command:

Response : '+00072.00

ND

Command:
Response:

A

special condition exists when using the
pulse modules. These modules differ from the other sensor input modules in that
they require an input trigger signal to obtain new data.

of

the

M1600,

not respond.

In order to escape this condition, a single control-C
to abort
value currently stored in the output buffer.
control-C character may interfere with the ND output data, causing a comrnunica­tions collision.

Read

The read data command
data. The output buffer (Figure
waiting for an input

Data

the

an ND command will wait indefinitely for new data and the module will

ND

(RD)

#I

ND

'1

ND+00072.009F

ND

command with the

If

no signal exists on the input

($03)

command. The aborted ND command will respond with the data

Be

aware that on an

is

the basic command used to read the buffered sensor

2.1

)

allows the data to be read immediately without

A/D

conversion. For example:

may be issued by the host

M1600

RS-485

frequency/

system, the

$1

Command:
Response:

Command:

Response:

Since
a special shortened version of the command is available.

without a two-lettercomrnand, the module interpretsthe string as an

the

RD

command is the most frequently used command in normal operation,

Command:
Response:

Command:

Response:

RD

*+00072.00

#I

RD

*I

RD+00072.1 OA4

$I

*+00072.10

#I

'1

RD+00072.10A4

If

a module

is

addressed

RD

command.

4-13

READ

The Read Events command reads the number

lated in the Events Counter. The output is a seven-digit decimal number. For
example:

EVENTS

(RE)

of

events that have been accumu-

Command:
Response:

Command:

Response:

The maximum accumulated count is

Events Counter stops counting.

Clear Events (CE) command.

The Event Counter count is not stored in nonvolatile memory.
the Event Counter will reset

The Remote Reset

Event Counter.

When reading the Event Counter with a checksum, be sure not to confuse the
checksum with the data.

Read

High

Alarm (RH)

$1

RE

*0000107

#1

RE

'1

RE00001

(RR)

command or a line break does not effect the value

to

074A

The

all

0's

9999999.

counter may be cleared at any time with the

upon power up.

When this count is reached, the

If

power is removed,

of

the

The Read High alarmcommand readsthevalueandtypeofthe high alarm previously

loaded

letter indicating the alarm type,

alarm value. For example:

The

the

by the

Command:

Response:
Command:

Response:

RH

command may be used to verify the data loaded into nonvolatile memory by

HI

command.

HI

command. The alarm type can be either latching or momentary.

"L"

for

$1

RH

*+00510.00L

#1

RH

*1

RH+0051

latching or

O.OOLF0

"M"

for

momentary, will

follow

A

the

4-

14

Read

The Read Low alarm command reads the value and type of the low alarm. The alarm

type can be either latching or momentary. A letter indicating the alarm type,

latching

Low

or

Alarm

"M"

for

(RL)

momentary, will follow the alarm value. For example:

"L"

for

Command:
Response:

Command:
Response:

The RLcommand may be used to verify data loaded into the nonvolatile memory with

the

LO

command.

Remote Reset

The reset command allows the host to perform a program reset on

microprocessor. This may be necessary ifthe module's internal program isdisrupted

by static or other electrical disturbances. Once a reset command is received, the

module will recalibrate itself.

seconds. For example:

Command:

Response:

$1

RL

*+OOOOO.OOL

#1

RL

*I

RL+OOOOO.OOLEE

(RR)

$1

RR

*

the

module's

The calibration process takes approximately

2

Command:

Response:

In general, the

by

the

RR

command. However,

Access Memory) has been lost, the

Any commands sent

a

NOT

READY

state

error.

#1

RR

*1

RRFF

of

the digital outputs and the event counter will not be affected

to

the module during the self-calibration sequence will result in

if

data in the microprocessor's

RR

command will

result

in a

RAM

full

power-up reset.

(Random

4-15

Read Setup

The read setupcommand reads backthe setup information loaded into the module's
nonvolatile memory with the Setup
command

(RS)

(SU)

is

four bytes of information formatted

command.

as

eight hex characters.

The response

to

the

RS

Command:

Response:

Command:

Response:

The response contains the module's channel address, baud rate, averaging con­stants,

Setup section of this manual for a full list of parameters contained within the setup
information.

When reading the setup with achecksum,

the setup information.

Read

The Read Zero command reads back the value stored in the Output Offset Register
(Figure

"C/"F,

Zero

2.1).

and other parameters. Refer

(RZ)

Command:

Response:

$1

RS

*31070142

#I

RS

'1

RS3107014292

$1

RZ

*+OOOOO.OO

be

to

the setup command

sure

not

to

confuse the checksum with

(SU),

and the

Command:

Response:

The data read back from the Output Offset Register may be interpreted
ways. The commands that

and Clear Zero (CZ).

4-16

#1

RZ

*1

RZ+OOOOO.OOBO

affect

this value are the Trim Zero (TZ), SetPoint (SP),

in

several

Setpoint

(SP)

The data specified by the setpoint command

Output Offset Register (Figure
applications

SP

command may be used

the RD or ND commands are used.

It is possible to load setpoint data that is beyond the output range of the sensor. In

this case, the setpoint can never be reached

is present.
To clear a setpoint, use the Clear Zero
The

SP

the Trim Zero (TZ) command.
this must
stored in the offset register may be read

and

is described in detail in the Digital

Command:

Response:

Command:

Response:

command will write over any data written into the Output Offset Register

be

accounted for

$1

SP+00450.00

*

#1

SP+00450.00

*1

SP+00450.00BO

2.1).

The

to

null out sensor

If

the Output Offset Register is used

by

the host

is

multiplied by

SP

command is useful in on-off controller

I/O

section of this manual. The

data

to obtain adeviation output when

by

the sensor data unless an overload

(CZ)

command.

before

back

using the

using the Read Zero

-1

and loaded into the

as

a trim value,

SP

command. The value

(RZ)

by

command.

The setpoint data or trim data in the Output Offset Register is saved in nonvolatile

memory.

Setup

Each

Read

address, baud rate, parity, etc. The EEPROM is a special type of memory that will

retain information even
to replace the usual array

equipment.
The Setup command is used

the EEPROM

is

has been devoted

Command

MI

000

Only Memory) which is used to store module setup information such

so

important

(SU)

module contains

if

power

to

taylor the module to your application. Since the Setup command

to

the proper operation of a module, a

to

its description.

an

EEPROM

is

removed from the module. The EEPROM is used

of

DIP

switches normally used

to

modify the user-specified parameters contained in

See

(Electrically Erasable Programmable

to

configure electronic

Section

whole

5.

section of this manual

as

4-17

The

SU

bytes

command requires an argument

of

setup information:

of

eight hexadecimal digits to describe four

Command: $1 SU31070182

Response:
Command: #1

Response:

Trim

Span

The trim span command is the basic means of trimming the accuracy
sensor module. The

to

trim the full-scale output

compensate for long-term drifts due
trim value of

be used to change the basictransfer function
use of the

(TS)

+lo%

TS

command may be found in the Calibration section.

Command:

Response:

Command:
Response:

*

SU31070182

'1

SU31070l8299

TS

command loads acalibration factor into nonvolatile memory

of

the signal conditioning circuitry.

to

aging

of the nominal calibration set at the

$1

TS+00500.00

of

the

analog circuits, and

of

the module.

*

#1

TS+00500.00

*I

TS+00500.00BO

factory.

It

is

intended only to

It is not intended to

Full

information on the

of

a M1000

has

a

useful

Caution!

provision
Unwarranted use of the TS command may destroy the calibration

can only be restored by using laboratory calibration instruments in a controlled
e nvi

ro

Trim

The

(Figure
offsets created by sensors such
to create a deviation output.

Example: Assume a
weight measurement. An inital reading of the load cell with no weight
applied may reveal

TS

is the only command associated with the span trim. There is no

to

read back or clear erroneous information loaded by the

n

rn

e

n

t

.

Zero

Trim Zero command

(TZ)

2.1)

to

null

out an undesirable offset in the output data. It may

M1511

an

Command: $1
Response:

*+00005.00

initial

RD

TS

command.

of

the unit which

is

used to load a value into the Output Offset Register

be

used totrirn

as

strain

bridge input module

offset

error:

gages.

It

may also be used to null out data

is

being used

with

a

load delb

r

4-18

With no weight applied, we would like to trim the output to read zero. To t r i m

the system, use the TZ command and specify the desired output reading:

Command:

Response:

The

TZ

command will load a data value into the Output Offset Register to force the
output
the Output Offset Register.
offset has been eliminated:

to

read zero. The module

Command:
Response:

Although the

be used to
nulled load cell system we performed this command:

TZ

offset

Command:

Response:

The new

data

output with no

$1TZ+OOOO0.00

(zero

output)

*

wiIl

compensate for

If

another output reading is taken,

$1

RD

*+OOOOO.OO

command is most commonly used to null an output

the output to any specified value. Assume thatwith the previously

$1

TZ-000100.00

*

load

applied would be:

any

previous value loaded into

it

will show that the

to

zero, it may

Command:

Response:

The load cell output
The offset value stored

be read backwith the ReadZero

command.
The SetPoint

Write

Each MetraByte module is write protected against accidental changing
limits, setup, or span and zero trims.
parameters, the
response to the

accept a write protected command.

fully completed, the module becomes automatically write disabled. Each write-

Enable

(SP)

(WE)

$1

RD

*-000100.00

is

now offset by -100.

by

the TZ command

(RZ)

commandandcleared withtheclearzero (CZ)

command will write over any value loaded by the

is

stored

in

nonvolatile memory and may

TZ

command.

of

To

change any

WE

command must precede the write-protected command. The

WE

command is an asterisk indicating that the module is ready to

After

the write-protected command is success-

of

these write protected

alarms,

4-19

protected command must be preceded individually with a WE command. For
example:

Command:

$1

WE

Response:

Command:

Response:

If

a

module

is

message other than
a command is successfully completed resulting in an

correct the command error without having

ERROR

The

MESSAGES

M1000

modules feature extensive error checking on input commands to avoid

#I

WE

*I

WEF7

write enabled and the execution of a command results

WRITE

PROTECTED, the module remains write enabled until

'

*

I

prompt. This lets the user

to

execute another

WE

command.

in

an error

erroneous operation. Any errors detected will result in an error message and the

command will be aborted.
All error messages begin with "?,,,followed

error description. The error messages have the same format for either the

#

I

command prompts. For example:

by

the channei address, aspace, and the

$

or

'

?I

SYNTAX

ERROR

There are eight possible error messages, and each error message description

begins with a different character. This makes it easy for a computer program

to

identify the error without having to read the entire string.

ADDRESS

There are four ASCII values that are illegal foruse asamoduleaddress:
CR

($OD),

is made

attempt to load an address greater than

BAD

CHECKSUM

ERROR

$

($24),

to

load an illegal address into a module with the Setup

and

#

($23).

The

ADDRESS ERROR will occur when an attempt

$7F

will

also

produce an error.

NULL($OO),

(SU)

command. An

This error is caused by an incorrect checksum included in the command string. The

module recognizes any two hex characters appended to a command string as a

checksum. Usually a BAD CHECKSUM erroroccurs due

to

noise or interference on

the communications line. In many cases, repeating the command will solve the

problem.

If

the error persists, either the checksum is being calculated incorrectly or

4-20

there is a problem with the communications channel.

transmissions may be obtained by using a lower baud rate.

In

some cases, more reliable

COMMAND

This erroroccurs when the two-charactercommand is not recognized by the module.

Often this error results when the command is sent with lower-case letters.

commands are upper-case.

NOT

READY

If

a module is reset, it

complete. Any commands sent to the module during the self-calibration period will
result in a

repeat the command.

The module may be reset in four ways: a power-up reset, a Remote

command, a line break, or an internal reset.

to ensure proper operation of the microprocessor. The timer may be tripped

microprocessor is executing its program improperly due to powertransients or static
discharge.

If

the NOT

to be sure

ERROR

performs

NOT

READY

READY

it

is within specifications.

error. When this occurs, simply wait a couple seconds and

error persists for more than

a

self-calibration routine which takes

All

modules contain a'watchdog' timer

30

seconds, check the power

2-3

seconds to

Reset

All

valid

(RR)

if

supply

the

PARITY

A

parity errorcan only occur

a parity error results from a bit error caused

line. Random parity errors are usually overcome
If

too many errors occur, the communications channel may have

a

slower baud rate may

Aconsistent parity errorwill result

In this situation, the easiest solution may be

communication. At this pointthe parity in the module may be changed to the desired
value with the Setup

The panty may also be changed or turned

SYNTAX

A

SYNTAX

is caused by having

or

in the wrong place. Table

ERROR

ERROR

ERROR

if

the module

be

used.

if

the host parity does not match the

(SU)

command.

will

result

too

few ortoo many characters, signs or decimal points missing

if

the structure

4.1

lists the correct syntax for all the commands.

is

setup with parity on (see Setup). Usually

by

interference

by

simply repeating the command.

on

the communications

to

be improved or

module

to

change the parity in the host to obtain

off

by using the Default

of

the command is

Mode.

not

correct.

panty.

This

4-21

VALUE

ERROR

This error results when
values can only contain decimal digits

Digital Output

WRITE PROTECTED

All

commands that write data into nonvolatile memory

accidental erasures. These commands

command or else a WRITE PROTECTED error will result.

(DO)

an

incorrect character

0-9.

Hex values used

commands can range from

must

be

is

used as a numerical value. Data

0-F.

are

write-protected to prevent

preceded with a Write Enable

in

the Setup

(SU)

(WE)

and

CHAPTER

5

SETUP

The MetraByte

options which gives them the flexibility to operate on virtually any computer or

terminal based system. The user options include a choice

address, and many other parameters. The particular choice of options for
module is referred

The setup information is loaded into the module using the Setup
command. The

if

nonvolatile memory contained in the

is

stored,

without losing the setup data. The nonvolatile memory is implemented with

EEPROM

The
used

the options are selected through the communications port. This allows the

setup

thousands

information stored in a module may be read back
Setup command (RS).

the module can be powered down indefinitely

so

EEPROM

for

option selection. The module never has to

to

be

M1000

to

SU

there are no batteries to replace.

has many advantages over

changed

of

feet

modules feature a wide choice of user configurable

as the setup information.

command stores 4 bytes

at

away

INFORMATION

(32

MetraByte

DIP

any time even though

from

the host computer or terminal. The setup

&

COMMAND

of

baud rate, parity,

a

(SU)

bits) of setup information into

module. Once the information

(10

years minimum)

switches or jumpers normally

be

opened because all

the

module may be located

at

any time using the Read

of

The following options can be specified by the

Channel address
Linefeeds

Parity

Baud
Alarm enable/disable
Alarm momentary/latching

CJC

RTD

Positivehegative edge trigger

Fahrenhe WCelsius

Echo

Communication delay

Number

La r g e-si

Small-signal filter

Each

chart
the setups, you can refer

information.

(odd, even, none)

rate

(300

disable

3/4

wire

of

displayed digits

g

nal

of

these options will be described in detail below. For a quick look-up

on

all options, refer to Tables

(124

to

38,400)

(M1300

(M1400

f

i 1 ter

con

constant

values)

series)

series)

(0-6

st

ant

(Mi600

characters)

5.1

-4.

to

Table

5.6

series)

Once you are completely familar with

for a summary of all

Setup

command:

of

the

setup

Command Syntax

The general format for the Setup (SU) command is:

$1

SU[bytel][byte S][byte 3][byte

A

typical

Setup command

would

look

41

like:

$1 SU31070182.

Notice that each
this example, byte 1 is described by the ASCII characters

equivalent of
contain exactly 8 hex

in a SYNTAX
conversion chart.

For the purposes of describing the Setup command, 'bit

order

bit

of

a

'bit

number': 7654

binary

The

setup data; therefore each SU command must

(WE)

character

caution:

may result in changing communications parameters (address, baud rate, parity)

which will result in

In

some

proper setups. The recommended procedure is to first use the Read Setup

command to to examine the existing setup data before proceeding with the

command.

data:

SU

command is write protected to guard against erroneous changes in the

command. To abort an

(an

Care must be exercised in using the

cases the

byte

is represented by its two-character ASCII equivalent.

binary

byte of data. 'Bit

'X

001

1

0001

(0-F)

ERROR.

0011

for

example) to generate a SYNTAX

a

loss

user

The Appendix contains a convenient hex-to-binary

of communications between the host and the module.

may

In

'31'

which is the

[31

hex). The operand of a SU

characters. Any deviation from this format will result

7'

0'

refers

SU

have to resort to using Default

to

lowest-order bit:

3210

0

0

0

1 =$31

command in progress,

(hex)

be

preceded by a Write Enable

ERROR,

SU

command. improper use

simply

command must

refers to the highest-

send a non-hex

and

try

again.

Mode

to

restore the

(RS)

SU

Byte

Byte

ASCII

command

'1'.

with the address
change the module address to
which
this:
changed from

The

1

1

contains the module (channel) address. The address is stored as

code for the string character used to address the module. In our example

$1

SU31070080

If

our sample command is sent

'l',

is

the ASCII code

$lSU32070080.

'1'

to

'2.

module

will

no

longer

,

the

which in

for

the character '2'. Now the command will

When

respond

first

byte

'31'

is

the

ASCII

to

a module, the EEPROM will be loaded

this

particular

'2' , byte 1 of the Setup command becomes

this

command

to

address

'l'..

case

is

sent, the module address is

code for the character

remains unchanged. To

look

the

'32''

like

When using the
record the new address in a place that is easily retrievable.

SU

command to change the address

of

a module, be sure to

The

only way to

communicate with a module with an unknown address is with the Default Mode.
The most significant bit

four

$OD,

ASCII

$24,

codes that are illegal

$23

which are

of

byte

ASCII

1

(bit

7)

must

be set to

for

use

as

an address. These codes are

codes for the characters

'0'.

In

addition, there are

NUL,

CR,

$,

and

$00,

#.

Using these codes for an address will cause an ADDRESS ERROR and the
setup
addresses that can be loaded with the
that only
greatly simplifies system debugging with a dumb terminal. Refer
for a list
used

Table

data

as

5.1

[EX

ASCII

21
22
25
26
27

28
29

2A

2B

2c

2D

2E

2F

30

31
32

33

34
35

36 6

37

38

39

will remain unchanged. This leaves a total

SU

command. It is highly recommended

ASCII

of

ASCII

codes for printable characters be used

codes. Table

5.1

lists the printable

addresses.

Byte

!

"

%

&

'

(

1

+

9

-

.

1

0

1
2

3

4

5

7

8

9

1

ASCII

iEX

3A

38

3c

3D

3E
3F

40

41

42

43

44
45
46

47
48

49
4A

48
4c

4D
4E

4F

50

Printable

ASCII

:

;

<

=

>

?

@

A

B

c

D

E

F

G

H

I

J

K

L

M

N

0

P

Characters.

1EX ASCII

51

52
53

54

55
56

57

58

59

SA

5B

5c

5D

Q

R

s

T

u

V

w

X

Y

2

\

1

5E

5F

60

61

62
63
64

65

66

67

-

'

a

b

c

d

e

f

g

IEX ASCII

68
69
6A

6B

6C

6D

6E

6F

70
71
72

73

74

75

76

77

78
79

7A

78
7c

7D

7E

ASCII

h

i

i

k

I

rn

n

0

P

q

r

S

t

U

V
W

X

Y

2

I

1

I

of

124

possible

($21

to $7E) which

to

Appendix

codes that may be

A

5-3

Byte

2

Byte 2 is used

channel; linefeeds, parity, and baud rate.

to

configure some of the characteristics

of

the communications

Linefeeds

The most significant bit

module. This option can be useful when using the module with a dumb

terminal.

(ASCII

return
MetraByte module can generate the linefeed
module will send a linefeed

is

cleared

When using the
in the checksum calculation.

All

responses from the M1000 are terminated with a carriage return

$OD).

is

Most terminals will generate a automatic linefeed when a carriage

detected. However,

(0),

no linefeeds are transmitted.

'C

of

byte 2 (bit

for

terminals that do not have this capability, the

(ASCII

command prompt, the linefeed characters are not included

$OA)

7)

controls linefeed generation by the

if

desired. By setting bit 7 to

before and after each response.

'1'

If

the

bit

Parity

Bits 5 and 6 select the panty to be used by the module. Bit 5 turns the parity on
and

off.

If

bit

5

is

'O',

the parity

bit

of

characters transmitted by the module

of

the command string is ignored and the parity

is

set to

'1'.

7

If

bit

5

is

'l',

the parity of command strings is checked and the parity

characters output by the module is calculated as specified by bit

If

bit 6 is

If

a

message. This

If

parity setup values are changed with the

SU

becomes effective immediately after the response message from the
command.

Baud

Bits
from eight values between
desired code.

The baud rate selection is the only setup data that is not implemented directly

after

module reset must occur. A reset

'O',

panty

panty error

command will be transmitted with the old parity setup. The new parity setup

is

even;

is

detected by the module, it

is

usually caused by noise

if

bit 6 is

'l',

parity is odd.

will

respond with a

on

the communications line.

SU

command, the response

Rate

0-2

specify the cammunications baud rate. The baud rate can be selected

300

and

an

38400

SU

command. In order for the baud rate to

is performed by sending a Remote Reset

baud. Refer to

6.

PARITY

Tabte

be

actually changed,

5.2

ERROR

of

to

the

SU

for the

a

(RR)

command, performing a line break (see Communications), or powering
This extra level
to the module
baud rate

refer to the Communications section.

of

of

write protection is necessary to ensure that communications

is

not accidently lost. This

an

RS-232C

string. For more information

is

very important when changing the

on

changing baud rate,

down.

Let's
module contains the setup data value of
to the

command with this module we would get:

Let's

baud

SU

protected:

This sequence of messages is done in
baud rate of the module. The module remains in

We

run

through an example

SU

command chart we can determine that the module is set for

linefeeds,

Command:
Response:

say we wish

command we must first send a Write

Command:

Response:

Command:

Response:

can

is

no

parity, and baud rate

'01

0'

(from

use

the Read Setup

$1

RS

*31070080

to

change

Table

$1

WE

*

$1

SU31020080

*

of

the baud rate to

5.2).

This

(RS)

command to check the setup data:

changing the baud rate. Assume our sample

'31

070080'.

300.

would change byte 2 to

300

If

9600

Enable

baud because that was the original

Byte 2 is

'07'.

By

referring

no

we perform the Read Setup

baud. The code for

'02'.

To perform the

command because

300

baud after this sequence.

SU

9600

is write

Command:

Response:

Notice that although the module
indicates a baud rate of

to

9600,

send

a

Command:

$1

RS

*31020080

9600

Remote Reset

$1

WE

is

(byte

(RR)

communicating

2

=

'02').

command

To actually change

(RR

Response:
Command:

Response:

Up

to this point

will not respond to any further communications at

running

9600

at

9600

baud to continue operation.

$1

RR

*

all

communications have been sent at

baud. At this point the host

computer

in 300

is write protected):

300

baud, the setup data

the

300

baud.

baud because it is

or

terminal must

baud rate

The module

now

be

set

to

5-5

If

the

module

is

incorrect. Try

The last resort

always

300.

does not respond to the

various

is

to

new

baud rate, most

baud

set the module to Default Mode where

rates

from the host until the module responds.

likely

the setup data

the

baud

rate

is

Setting a string
consideration.

Bits

3

and

These

two

4

bits

Refer

of

Ts.

Table

BYTE2

I

FUNCTION

LINEFEED

NO

NO PARITY

IN0

EVEN PARITY

5.2

Byte

LINEFEED

PARITY

of

RS-232C modules

to the Communications section

byte 2 are not

2:

Linefeed,

used

Parity

by

the

and

I
I

to a new

M1

000

Baud

DATA BIT

~~

76543210

1

0

00

10

01

baud

for

series and should be

Rate.

rate requires special

instructions.

set to

I

I

I

IODD

I

NOT

I38400

19200
9600

4800

2400

1200

600

1300UD

PARITY

USED

BAUD

BAUD

BAUD

BAUD
BAUD
BAUD

BAUD

~ ~~~

I

I

I

I

11

~~~

~~

xx

000
001

010

011

100

110
111

I

I
I

1

5-6

Byte

3

This byte contains the setup information for several seldom-used options. The

default value for this byte is

'01'.

Alarm

Bit 7 determines if the outputs
module terminal block.

terminal block. In this condition the outputs are controlled by the Digital Output

(DO)

This bit

bit to

low

Bit 6 determines whether the
that
controlled

High

Bit 5 determines whether the

latching. Bit 5 is

Disable

RTD

Trigger

Enable

command.

is

also controlled by the Enable Alarms

'1'-

The Disable Alarms

Alarm

the

Latch

alarm is latching;

by

Alarm

the

LO

Latch

If

also

CJC

3/4

Wire

Edge

Setect

from

If

the value is

bit 7 is

'1'

the alarms are connected

(DA)

LO

'0'

indicates a momentary alarm. Bit

Alarm

(LO)

command.

HI

controlled individually by the

the LO and

'0'

the alarms are not connected to the

command

Alarm is latching

Alarm is latching

clears

HI

alarms are connected to

to

the terminal block.

(EA)

command which

the bit to

or

or

HI

Alarm

'0'.

momentary.

momentary. A'1' indicates

(HI)

A

'1'

command.

sets

the

indicates

6

is

also

The setup information stored in bit 4 has different meanings depending on the

M1000

Disable

input modules.
disabled. The module calculates
junction temperature of
cases where remote

RTD

modules.

compensation calculation for

calculates the correct lead cornpensation for 3-wire
may result

Trigger

frequency and pulse modules. Bit 4 determines the

trigger the measurement cycle.

model number.

CJC;

3/4

this

Wire;

if

Edge

this functions pertains only to the

If

the bit

the module is

Select;

functions pertains only to the

If

the bit is set to

0°C.

CJC

This setup

is used.

is

set to

not

this function pertains only to the M1600

Normally

4-wire

set

to

'1'

the Cold Junction Compensation is

the

temperature output with a fixed cold

is

useful for calibrating the module

this

'l',

the module provides the correct lead-

RTD's.

the correct sensor

If

bit 4 is '1' then the measurement

If

Mi300

bit

is

cleared to

the bit is cleared

RTD's.

series

M1400

'0'.

series of RTD input

Measurement errors

type.

polarity

of

of

thermocouple

to

'O',

the module

the

edge

or

series

used to

cycle

5-7

in

is

started

negative-going edge
frequency inputs.
deviates from

CelsiuslFahrenheit

on

a

positive-going edge. The measurement cycle is started

50%

duty

on

if

bit 4 is

It

is primarily used with pulse inputs where the pulse train

cycle.

'0'.

In general, this setup has very little effect on

the

The default scaling
by making bit
modules that
The scaling factors
setpoints must be modified by appropriate commands to reflect a scaling
change (see Figure

Echo

When

received

multiple RS-232C modules. Echo

module. Bit
Communications section for a more complete description.

Delay

Bits

module response. This delay time is useful

enough to capture

particularly

added

Each unit

one character with the baud rate specified in byte

delay

number of delay units is selectable from 0 to 6 as shown in Table

bit 2 is

0

and

to

at

do

on

the communications line. This option

1

specify a minimum turn-around delay between a command and the

true

the typical command delays listed in the Communications section.

of

delay specified by

300 baud is 33.3

for

temperature output modules is Celsius which is selected

3

=

set

2

for systems that use software

To change the scaling to Fahrenheit, set bit 3 to

0.

not have temperature output must have bit 3 cleared to zero.

are

operative only on the sensor

2.1).

to

'l',

the

M1000

is

must be cleared

data

from quick-responding commands such as

bits

ms;

for

module will retransmit any characters

optional for systems with a single RS-232C

to

'0'

on

OR

0

and I is equal to time required to transmit

38.4 kilobaud the delay

data;

is

RS-485

host systems that are not fast

UART's.

2.

HI

and

LO

limits and

necessary to 'daisy-chain'

models.

The specified delay is

For example, one unit

is

0.26 ms. The

5.3.

See

RD.

'1'.

All

it

has

the

This is

of

In

some systems, such as

by a linefeed (LF). The
command terminated by a
communications collision between the linefeed and the

module should be setup to delay by 2 units.

IBM

MI000

CR

BASIC,

a

carriage return

modules will respond immediately after

and will ignore the linefeed.

5-8

(CR)

is always folIowed

To

module

response, the

avoid

a

a

Table

5.3

Byte

3

Options.

FUNCTION

ALARMS
ALARMS

~~~~~~~~ ~ ~~

OFF

ON

HIGH ALARM MOMENTARY

HIGH

_.

ALARM LATCHING

..

__

-

._

.

LOW ALARM MOMENTARY
LOW ALARM LATCHING

CJC

(

Df

300's

NO

CJC

(

3

WIRE

4

WIRE

-

STARTING EDGE ( D1600'S

+

STARTING EDGE ( DISOO'S

CELSl

(

D1400'S

(

D1400'S

US

)

DI300'S

)

)

1

)

)

DATA

BIT

76543210

0

1

~ ~~

0

1

0

1

0

1

0

1

I

0

1

0

I

FAHRENHEIT
NO ECHO
ECHO
NO DELAYS

2

BYTE TIME DELAYS

4 BYTE TIME DELAYS

6

BYTE TIME DELAYS

I

I

I

0

1

00

011

101

11

5-9

Byte

4

This setup byte specifies the number
constants.

Number

For ease

common 7-digit output consisting
digits. Typical output data
tion
the resolution

measurement system. In such cases, the trailing digits
display meaningless information. Bits 6 and 7 are used to insert trailing zeros

into the output data to limit the output resolution and mask-off meaningless
digits.

Bit

0

0

1
1

of

7

of

displayed digits

of

use, the data outputs of

the

A/D

converter is 1 part in

of

Sit

6

0

1

0

1

looks

the output format is much greater than the resolution of the

XXXXO.00
XXXXX.00
XXXXX.XO
XXXXX.XX

of

displayed digits and the digital filter time

all

M1000 modules are standardized to a

of

sign, 5 digits, decimal point, and two more

like:

+00100.00.

50,000

(4

displayed digits)

(5

displayed digits)

(6

displayed digits)

(7

displayed digits)

or about 4

However, best-case resolu-

112

digits. In some cases,

of

the response would

For example, the M1411 model for RTDs has
appropriate number of digits for this module is
has no meaningful data.
resolution to 1 degree. To do this, select bits 6 and 7

this selection, the rightrnost-two digits will always

The number

command.

Large

Small Signal

The MI 000 series modules contain a versatile single-pole, low-pass digital

to

The digital filter offers many advantages over traditional analog filters. The

filtering action is done completely in firmware and

drifts, offsets, and

constant is programmable through the Setup
changed at any time, even

The digital filter features separate time constants for

variations. The Large Signal Filter time constant is controlled

time constant

Signal Filter,

smooth out unwanted noise caused by interference or small signal variations.

of

displayed digits affects

Filter,

circuit

is

used when large signal variations

In

some cases, the user may want to limit the output

Bits

3,4,5

Bits

0,1,2

noise typically found

if

the module is remote

only

.1

degree output resolution. The

6,

to

mask

be

set to

data received from an

is

in

analog filters. The filter time

(SU)

from

are

off

the .01 digit which

to

display 5 digits. With

'0'.

RD

not affected

command and can be

the host.

large

present

by

component

and

small

by

bits 3,4,5. This

on

the input. The

or

ND

filter

signal

5-10

Small Signal Filter time constant is controlled by bits
constant is automatically selected when input signal variations are small. The

microprocessor

constant after every A/D conversion. The constant selected depends on the

magnitude
digits displayed. The microprocessor always keeps the value of the last
calculated output to compare to a new data conversion.
from the last output by more than ten counts
signal time constant is used in the digital filter.
conversion differs from the last output value by
displayed digit, the small signal time constant is used. Let's

The

M1411

The standard number-of -displayed-digits setup for this module is 6 digits,
specified
selected

1

.O

degree:

by

if

in

the MetraByte module automatically selects the correct filter

of

the change of the input signal and the setup for the number

of

the last displayed digit, the large

If

the result

less

module

byte

a

new input conversion differs from the previous value by more than

for

RTDs has a standard output resolution of

4

of

the setup data. Therefore, the large signal filter will be

0,1,2.

If

of

than ten counts

look

This filter time

the new data differs

the most recent

at an example:

of

the last

.I

degrees.

of

A/D

Previous

+00100.00

+00100.00
+00100.00

+a01

-00050.50

-00050.50

If

the number
selection is also affected.
example

n this case the large signal time constant

the old by more than

Previous data

+00100.00
+DO1

+00100.00
+00100.00

-00050.00

-00050.00

data New data Filter selected

+00100.50

+om

01

so

+00099.90

00.00

is

00.00

changed to

+00098.90

-00050.00

-00060.00

of

displayed digits is changed to reduce output resolution, the filter

If

the number

5,

the output resolution becomes

10.0

degrees:

New

data Filter selected (large/small)

+00105.00

+00111

+00091

+00085.00

-00045.00

-00039.00

.OO
.OO

small

large
small

large

small
large

small
large
small
large
small
small

of

is

used

(large/small)

displayed digits in the previous

1

.O

degree.

if

the new reading differs from

5-1

1

Large

Signal

Time

Constant

The large signal filter time constant is specified by bits
specified from 0 (no filter) to

is the time required for the output

Small

Bits

to the ones

amount
small signal time constant should be larger than the large signal time constant.

This

to

Signal

0,1,2

of

gives stable readings for steady-state inputs while providing fast response

large signal changes.

Table

FUNCTION

+XXXXX.OO

5.4

Time Constant

specify the filter time constant for small signals. Its

for

the large signal

small signal filtering

Byte 4 Displayed

DISPLAYED DIGITS

16

seconds. The time constant for a first-order filter

to

reach

filter.

such

Digits

63%

of

its final

Most sensors can benefit from a small

as

T

=

0.5

and

Filter Time Constants.

DATA BIT

76543210

01

sec.

3,4,5

of byte

value

for a step input.

In most applications, the

4.

values

I

It may be

are similar

+XXXXX.XO

+XXXXX.XX

NO LARGE SIGNAL FILTERING

0.25

SECOND TIME CONSTANT

0.5

SECOND TIME CONSTANT

1

.O

SECOND TIME CONSTANT

2.0

SECOND TIME CONSTANT

4.0

SECOND TIME CONSTANT

I

8.0

SECOND TIME CONSTANT

NO SMALL SIGNAL FILTERING

0.25

SECOND TIME CONSTANT

0.5

SECOND TIME CONSTANT

1

.O

SECOND TIME CONSTANT

2.0

SECOND TIME CONSTANT

4.0

SECOND TIME CONSTANT

8.0

SECOND TIME CONSTANT

DISPLAYED DIGITS

DISPLAYED DIGITS

10

11

I

000

001
010
011

100
101

110

000

001
010
011
100
101

110

..

t

I

16.0

5-12

SECOND TIME CONSTANT

I

11

11

Setup Hints

Until you become completely familiar with the Setup command, the best
method
that the change has been made correctly. Attempting to modify all the setups at
once can often lead
recourse
changing one parameter at a time. Use the Read Setup
examine the setup information currently in the module as a basis for creating a

new setup. For example:

of

changing setups is to change one parameter at a time and to verify

to

is

confusion.

to

reload the factory setup as shown in Table

If

you reach a state

of

total confusion, the best

5.5

and try again,

(RS)

command to

Assume you have

may be used in a daisy-chain (See Communications).

setup with the Read Setup command:

Command:
Response:

By referring
From the
hexadecimal representation
set to

3

command, changing only byte

is

'1'.

05.

to

RS

This results in binary

To perform the

Command:

Response:
Command:

a

M1111

$1

RS

'31

Table

command we see that byte 3 is currently set to

5.3,

unit and you wish to set the unit to echo

Read

0701

C2

we find that the echo

of

binary

0000

SU

command, use the data read out with the RS

0000

0101.

is

controlled by bit

0001.

The new hexadecimal value of byte

To

set echo,

3:

$1

WE

(SU

is

write-protected)

*

$1

SU310705C2

01.

Response:

Verify that the module is echoing characters and the setup is correct.

out

the current

2

of

This is the

bit

2

so

that it

byte

must be

3.

By using the
problems associated with incorrect setups may be identified immediately. Once

a

satisfactory setup has been developed, record the setup value and use it to

configure similar modules

If

you commit an error in using the Setup command, it is possible to lose

communications with the module. In

Default Mode to re-establish communications.

The

DA,

are associated with alarms.
read back with the Read Setup

the data previously written with the Setup (SU) command.

EA,

RS

command and changing one setup parameter at a time, any

this

case, it may be necessary to use the

HI, and

LO

commands affect some of the bits

If

these commands are performed, the setup data

(RS)

command may not correspond exactly with

of

the

setup data that

5-13

Table

(All

5.5

modules

Factory

from

the

Setups

factory

by

are

Model.

set

for

address

'l',

300

baud,

no

parity)

Model

M111

X,

M121

X,

M112X, M124X
M113X,M114X

M13XX

M14XX

M15XX

M16XX
M17OX

M123X, M125X

Setup

Message

31 0701
31 0701
31 0701

C2

82
42

31 0701 42
31 0701
31
31

31

0701

0701

0701

82

C2

CO

00

CHAPTER

6

DIGITAL I /

The

M1000

equipment. The functions available are:

1

)

2) Digital Inputs

3)

4)

Digital

A

digital output consists of
using the Digital Output
outputs implemented depends on the specific MlOOO model number.
sensor modules contain two digital outputs and the M1701/2 has eight digital
outputs. The open-collector configuration
versatility in interfacing

such

withstand
emitter

as

series features versatile digital

Digital Outputs

Alarm Outputs

Events Counter

Outputs

an

(DO)

command (See Figure

to

solid state relays

TTL

or

CMOS.

UKI

to

30V.

of

each transistor is tied to the

Each digital output can sink up

Power

in

110

capability

open-collector transistor controlled by the

6.1).

is

used to provide maximum

(SSR's)

the transistor must be limited to

GND

terminal on the input connector.

or

0

FUNCTION

to

interface to auxiliary

The number

to

standard logic levels

to

30mA and can

300

of

mW. The

host,

digital

Most

DIGITAL

INPUT
OUTPUT

PORT

Figure

+vs

msim

1

R

1

BR2

to

30rnAMax.

6.1

Digitat Outputs Used With Relays.

+YS

0

Limit

Current

A typical connection

solid state relay

to control

logic input is shown in Figure 6.2. In some cases, the common-mode voltage

the

GND

logic input to be interfaced. This may occur when the module is powered
remotely. In this case, an opto-isolator may be used to eliminate the comrnon­mode voltage. See Figure
transistor may not

AC

power to alarms, heaters, pumps, etc. A typical connection to

terminal may be significantly different from the ground potential

of

a digital

is

controlled by the

be

more than

I/O

output is shown in Figure 6.1. In this case, a

6.2.

30

MlOOO

In all cases, the current switched by the

mA.

module. The

SSR

can then be used

of

a

of

the

Figure

Only three commands can effect the Digital Output. The Enable Alarms
and Disable Alarms (DA) commands

DOl/HI pin outputs.
Alarms (DA) command. The Enable Alarms
two pins
do not affect the other digital outputs,

controlled by the host with the Digital Output (DO) command.

If

the module loses
remain off until switched by a Digital Output
shared pins, DOBILO and DOl/H1
information

The digital outputs are not affected

reset caused by a line break.

as

alarm outputs. The Enable Alarms and Disable Alarms commands

power,

is

stored in nonvolatile memory.

6.2

Digital

To

route digital outputs

the digital outputs are turned

Outputs

select

D02-DO7.

(DO)

is

not affected

by

the Remote

the function

Used

to

(EA)

command. The function

With

these pins, use the Disable

command configures these

The

if

power

Reset

Logic

of

the

D00/LO

digital outputs are

off.

The outputs will

is

lost, since this

(RR)

command or a

(EA)

and

of

the

DlGfTAL

INPUTS

Digital inputs are used to sense switch closures and the state
The inputs are protected to voRages up to
the logic

Input (DI) command. Voltage inputs less than 1 V

Signals greater than

affect on the inputs.

Switch closures can be read by the digital input

between

additional

The pull-ups supply only

low current operation should be used.

necessary to provide extra pull-up current with an external resistor. The resistor

should be

Connection to logic outputs is shown in Figure

isolation and where common-mode exists between the

signal being sensed.

Digital inputs may be used
modules offered by many manufacturers.

"1"

condition (see Figure

3.5

V

GND

parts

tied

terminal and a digital input. Internal puII-ups are used

are unnecessary.

between the switch and

6.3).

are read as

0.5

mA; therefore, self-wiping switches designed for

+V.

to

sense

k30V

Digital inputs can be read

'1'.

For

AC

voltages

and are normally pulled up

No

other commands have any

by

simply connecting the switch

other

types

6.2.

of

Opto-isolation is used for

M1000

by

using isolated sensing

of

digital signals.

by

the Digital

are read back as

switches, it may be

module

and the

to

'0'.

so

Figure

6.3

Digital

Inputs

6-3

EVENT

The Event Counter input is connected to the Digital Input 0 terminal. It can be

used to count any

interfacing techniques described

pulses must meet the specifications in Figure

Switch inputs are filtered to eliminate contact bounce.

COUNTER

low

speed event that occurs on the

for

Digital Inputs

DI0/EV

may

6.4

to avoid missing counts.

input. Any

be

used. The input

of

the

The Event Counter

maximum accumulated count

counting stops. The Event Counter

Events

The Event Counter

module
Remote Reset

(CE)

goes

command.

down.

(RR)

is

read

is

not nonvolatile and the count will be lost if power

Upon

command or a line break will not

by

using the Read Events

is

9,999,999.

power up, the counter

(RE)

command. The

If

the maximum count is reached,

may

be cleared to zero with the Clear

is

cleared to zero.

P

c5ydc

affect

the counter.

to

the

The

64

EV

INPUT

+5Y

0y

50SdDutyCycle
60

Hz

Figure

6.4

Max.

Events

Single

Pulse

12m3.Min. 15ms.Min.

Single

Puke

Counter Circuit.

ALARM

The

the sensor input value to downloaded HVLO limit values stored in memory (see

HI and
special HI and

OUTPUTS

M1

000

LO

sensor input modules perform HI/LO limit checking by comparing

commands).

LO

digital outputs.

The result of the limit check can be used to control

The DO0/LO and

using the Enable Alarms (EA) command. After performing
state of the DO0/LO and
The

EA

command does not affect the other digital outputs, D02-DO8. The

Disable Alarms

pins whereupon they are controlled by the Digital Output
Since the Alarm Outputs share the same circuits with the Digital Outputs, all

electrical interfacing considerations are the same.
Alarm limit values are loaded into the module with the Low limit (LO) and Hi limit

(HI)

commands. The limit values are stored in nonvolatile memory

not be lost when power

specify whether the alarms are momentary or latching.

as momentary, the alarm is activated as long as the alarm condition exists. The
alarm output will turn off when the input is within limits. A Latching alarm is
activated when the specified limit

input value returns within limits.

Clear Alarms
when the measured sensor input is greater than the high limit loaded in with the

HI

command. The LO alarm output is turned on (sinking current) when the input

value is

less

than the stored low limit.

DOl/HI

(DA)

command

output pins can be configured to be alarm outputs by

an

EA

command, the

DOl/HI

pins will be controlled by the alarm settings.

is

used to disconnect the alarms from the output

(DO)

command.

so

is

removed. The

is

A

(CA)

command. The HI alarm output is turned on (sinking current)

HI

and LO commands are

If

an alarm is specified

exceeded and will remain on even

Latching alarm can be turned

also

off

they will

used to

if

the

with the

The alarm limit values may be read back at any time using the Read

Read High (RH) commands.

ON-OFF

The alarm capabilities
construct simple ON-OFF controllers that operate without host intervention. In
fact, since

can

The simplest controller connection is
the process.

controlling
temperature, set the low limit to the setpoint desired and specify the alarm

output to
temperature measurement exceeds the

CONTROLLERS

of

the

Ml000

all

the alarm information is stored in nonvolatile memory, the module

act as a stand-alone controller with the communications lines disconnected.

A

typical application would have a temperature input module

a

heater, as shown in Figure

be

momentary,

Use the

sensor-input modules

to

use a momentary alarm output to control

6.5.

LO

alarm output to control the heater.

low

limit, the heater will be turned

To

may

maintain

Low

(RL)

or

be utilized to

a

constant

If

the

off.

6-5

When the temperature goes below the limit, the
turning on the heater.

The

negative feedback action

LO

alarm output goes on,

of

the control output

will

keep the temperature at the desired value. The high limit is still available to
activate an alarm or shut down the system if

the

temperature

goes

out

of

limit.

66

I

Ill

I

~

ON-OFF CONTROLLER

The simple single-value controller,

that may not

controlled.

be

acceptable, particularly when high-power equipment

To

lengthen the control cycle and

WITH

HYSTERESIS

by

its very nature, suffers from erratic output

is

to

make the control action

being

smoother, hysteresis (also known as dead band) is often used in on-off

controllers. With hysteresis, the process variable is controlled between the two

setpoints in order to lengthen the duty cycle of the control output. To increase

the control duty cycle, the hysteresis, or difference between the setpoints, must

be increased. Figure
The high and low alarm limits on the

6.6

shows the effect of hysteresis on the control output.

MlOOO

sensor modules may be set to
provide on-off control with hysteresis. The two limits specify the two control
setpoints. The difference between the high limit and the low limit is the
hysteresis value. The high limit must be greater than the low limit
operation. The alarm output used to control

Latching mode.

If

the control output is turned on, it will remain on until the input

the

process must be set to the

for

proper

data exceeds the second alarm value. At this point the control output is turned

Off.

A

typical example
temperature sensor module such as a
used

to

regulate the temperature

sense the oven temperature. The

(SSR)

which in turn controls the oven heater. The Enable Alarms

command must be used

regulated temperature is
Mode with the
limit to
between the

105°C

two

temperature will oscillate between

of

a

controller with hysteresis is illustrated in Figure

M1311

of

an oven. The thermocouple is used to

LO

alarm output controls a solid state relay

J-Thermocouple model maybe

6.5.

A

(EA)

to

activate the alarm outputs. In this case the desired

100OC.

LO

command. The

The

Lo

alarm is set to

HI

alarm command is used

95°C

in

the latching

to

set the upper

in the momentary mode. The total hysteresis is the difference

alarm values,

or

95°C

10°C.

and

In the steady state condition, the oven

100°C

(ideally).

Assume the oven temperature is below
loaded into the low limit, therefore the
low alarm is

temperature goes above the

set

for latching mode, the control output stays on even as the oven

95OC

the temperature reaches the value loaded into the high limit, in this

At

this point the latched

LO

alarm

95°C.

LO

This value is less than the value

alarm output is turned on. Since the

low limit. The control output will stay

case

is

turned

off,

turning

off

the heater. The

control output will remain off as the oven cools down through heat

When the oven

process repeats indefinitely. The control signals are shown

cools

to

95'C,

the

LO

alarm is again turned on, and the control

in

Figure

6.6.

on

until

105°C.

losses.

67

6-

8

In this case the high alarm
have been set to the latching mode without affecting the LO alarm output.
However, the output

set to Latching, the alarm output

Either alarm output may be used for control depending on which one will result
in negative feedback. For example, in a refrigeration system, the
be used to control the refrigeration compressor and

only to set the desired hysteresis value.

at

was

set to momentary mode. The high alarm could

the

HI alarm terminal would change.

is

simply the complement of the LO alarm.

the

If

low

alarm value

the high alarm is

HI

output may

is

used

SETPOlNT

In

the preceding example, the

hysteresis value around a desired setpoint. To change the desired setpoint,

both the
operation, the Read Data (RD) or
actual value of the process variable.

The
affecting the desired hysteresis by using the Setpoint
Setpoint command
offset register (see Figure
added to the data derived from the sensor input. For instance,

is

+00100.00

command
value into the offset register to null out the sensor data.

$1

SP+OOlOO.OO

is to load the output offset register with
result in the deviation of the input data from the downloaded setpoint value.

low

MlOOO

and high alarm values must

modules provide a means

is

used to load the desired control value into the output

and the output offset register contains

will

yield an output of

is

given to a module with address

2.1).

low

and high alarm limits are used to specify

be

changed. In this type of controller

New

Data

(ND)

commands will read out the

of

downloading a setpoint value without

(SP)

command. The

The value

+00150.00.

in

the output offset register is always

if

the sensor data

The Setpoint command loads

-00100.00.

+00050.00,

1,

the effect of the command

An

RD

a

If

the command

command will now

a

Read Data

a

A

careful

output offset is added the input

mand, the high and low alarms must be loaded with the hysteresis values

referred
the hysteresis was set to
When using the

low

Latching modes
described.

Let's
desired oven temperature is

load the

hysteresis band
the low limit to
and low limits are now used solely to define the hysteresis band.
temperature is

is

-10°C.

look

at Figure

to

the deviation from the setpoint value. In the oven controller example,

SP

limit would be set to

of

look

at the oven controller again using the Setpoint command. The

100°C

value into the temperature module.

of

-00005.00

low,

This value exceeds the low limit and the LO alarm control output is

2.1

command, the high limit would

the alarm limits are used in the same manner

f

5

from the nominal temperature

say

90°C,

will reveal that the alarm limits are checked after the

data.

k5"C

-00005.00

100°C.

latching and the high limit to

the resulting deviation from the setpoint

To construct a controller using the

from the desired control temperature of

be

set to

to get the same hysteresis affect.

This time we'll use the

As

of

+00005.00

as

previously

SP

command

before, we would like a

100°C. In this case, set

+00005.00.

The high

If

the oven

of

SP

com-

100°C.

and the

The

100°C

to

turned on

measured temperature exceeds

setpoint

high limit is exceeded, the latched
heater. The control action is identical to the controller described in Figure

to

activate the heater. The latched

105OC.

is

greater than

k

5OC,

the value loaded into the high limit.

LO

LO

alarm will stay on until the

At this point the deviation from the

alarm output

is

turned

off,

turning off the

When the

6.6.

The benefit of using
change the setpoint value.

registers and does not have to be changed when a new setpoint is used.

The

SP

command makes it particularly easy to construct a controller whose
setpoint
command can also
output

The setpoint value may be
The

command will always read back the setpoint value with the sign changed.
The setpoint value

command).
calibration trim value, the
offset calibration trim is not necessary and the trim value would read back as

+OOOOO.OO

be
download setpoint values the host must then subtract the trim value from the
desired setpoint to derive the proper data
trim, use the

previously read

is

a

time varying function downloaded from a host computer. The

is

desired.

RZ

simply reads back the contents

In

using the Read Zero

read

and stored by the host before the

SP

back

SP

command is that only one command is necessary

The hysteresis is stored in the

be

used without control functions whenever a deviation

read

back by using the Read Zero

of

the output offset register.

is

stored in the same register

cases where the

SP

command will erase the trim. In most cases, an

command to download the negative of the

with the RZ command.

output

(RZ)

command.

for

as

the output offset trim (see TZ

offset register is used to hold

If

the trim is non-zero,

SP

command

the

SP

command. To restore the

HI

and

LO

(RZ)

command.

The RZ

is

executed. To

trim

that was

alarm

SP

it

must

lo

a

6-10

CHAPTER

7

POWER

MetraByte modules may be powered with an unregulated
Power-supply ripple must be limited to
ripple voltage must be maintained between the

All

power supply specifications are referred to the module connector; the effects

of line voltage drops must be considered when the module

remotely.

All

Ml000

efficiency over the

inversely proportional to the line voltage. M1
excitation consume a maximum of
determining the power supply current requirement.

volt power supply will be used to power four modules. The total power

requirement is 4 X

24

=

.I

For modules with sensor excitation, consult individual data sheets for power

requirements.

modules employ an on-board switching regulator to maintain good

10

to

30

volt input range; therefore the actual current draw is

.75

=

3

watts. The power supply must be able to provide

25

amps.

5V

peak-to-peak, and the instantaneous

10

and

30

volt limits at

000

modules without sensor

.75

watts and this figure should be used in

For

example, assume

SUPPLY

+I0

to

is

+30V

all

powered

dc.

times.

a

24

3

/

In

some cases, a small number

power from

output on the

Small systems may be powered by using wall-mounted calculator-type modular

power supplies. These units

retail electronics outlets.

For best reliability, modules operated on long communications lines

should be powered locally using small calculator-type power units. This
eliminates the voltage drops
communications signals. In this case
local power supply. The Ground terminal must
provide a ground return for the communications

All

MetraByte modules are protected against power supply reversals.

a

host

RS-232C

computer or terminal. Many computers provide a +15 volt

D25

connector.

of

modules may be operated by “stealing”

are

inexpensive and may be obtained from many

(>500

on

the Ground lead which may interfere with

the

V+

terminal

be

loop.

is

connected only to the

connected back to the host to

feet)

CHAPTER

8

TROUBLESHOOTING

Symptom:

*

No

module response

Assuming that the module is in a system, complete the following steps before

removing it from the system. These steps will check the obvious things before
removing.

1.

and Ground terminals to ensure that the power supplied is between

+30

2.

that there are no breaks in the lines.

3.

rate switch is set to the correct position.

If

system

Using a voltmeter, measure the power supply voltage at the module +Vs

Vdc.

Check to see that the communications lines are connected properly and

If

the above steps do not correct the problem, remove the module from the

and

No

module

Events

Error

you are using the

return

counter

in

displayed

to

the bench. Complete the following

response.

not

counting properly.

vatue.

RS-232C

to

RS-485

+10

and

converter, make sure the baud

steps.

1.

and Ground terminals

2.

proceedure. Your terminal should be set to

you

3.

4.

Retu rn key.

If

responds, send
setup message is correct.

1.

2.

3.

above procedure basically makes sure that the module and the system are

speaking the same language. Reinstall module in the system and

Connect a working power supply (between

on

the module.

Connect the modute to a dumb terminal

300

are using the

Connect a jumper wire from the Ground terminal to the Default' terminal.

Turn

the module still does not respond, call the factory for assistance.

Check

If

daisy-chaining

If

using byte time delay make sure that the proper delay is set. The

RS-485

the power supply on, type

a

that the baud rate is correct.

$1RS

RS-232C

converter, make sure its baud rate is set

command to see

modules, be sure that the echo bit

$1RD

if

+10

and

+30

Vdc) to the

as

in

the

Quick Hook

baud rate and no parity. Also

to

on the terminal and press the

the information in the module's

is

try

300

baud.

If

the module

set to

again.

1.

Vs

Up

if

Events

1.

counter

not

counting

Check that the frequency

properly

of

the signal, being counted is

less

than

60Hz.

Error

1.

in

displayed

Make sure that
scaled

by

the

OF

value

the

"C/OF

equation.

bit is set to a

0.

Otherwise the values

will

be

CHAPTER

9

CALIBRATION

The

MI000

calibration interval
Calibration constants are stored in the EEPROM and may be trimmed using the

Trim Span (TS) and Trim Zero (TZ) commands. There are
Calibration procedure

module is initially calibrated at the factory and has a recommended

of

one year.

no

pots

to adjust.

is

as

follows.

Voltage

Zero (CZ) command. Zero trims are not neccessary due
function. Apply a known calibrated voltage or current to the input
The calibrated stimulus

output

voltage or current must be better than the rated accuracy

in most cases is
obtain an output reading.

calibration

connections or use a different input value
operating range of the module.

To

trim the output, use the Trim
command should correspond to the desired module output. After performing
the

TS

a

M1121

and current inputs:

should

of

the modules for best results. Obviously, the accuracy

0.02%

is

necessary.

command, verify the trim using the RD command. For example:

module, the following steps should be performed.

1.

Clear the output offset register.

Command:

$1

of

WE

Response:

clear

full scale. Use the Read Data (RD) command to
If

the output corresponds

If

the output is in overload,

the

be

adjusted to

Span

(CZ

(TS)

is

output offset register using the Clear

to

the built-in auto-zero

of

the module.

be

near

90%

of

the

of

the calibrated

of

the module, which

to

the applied input, no

check

to

obtain an output within the

command. The argument

write

protected)

the circuit

full

of

the TS

To

scale

trim

Command:
Response:

2.

Apply an input voltage near

use

a

+900

output reading.

Command:

Response:

In this case, the output

To

trim:

Command:
Response:

$1

CZ

*

90%

of

rated full scale.

mV

input voltage that is accurate to at least

$1

RD

*+00900.30

of

$1

*

the module is

WE

(TS

off

by

300

is write protected)

pV.

In

this

0.02%.

case

we will

Obtain an

Command:
Response:

$1

TS+OO900.00

*

This sequence will trim the output to the desired calibrated value

of

+00900.00.

Verify:

Command:

Response:

The module

Thermocouples:

Compensation
command. The module

Perform the calibration as described
recommended calibration points. Due to the nonlinear nature

thermocouples, it may be necessary

desired output. After calibration is complete, be sure to enable the cold junction
compensation by clearing bit 4 in byte 3 of

RTD:

avoid

calibration.
command sequence described
to the nonlinear nature
to obtain the desired output.

Use a calibrated

lead resistance errors. The resistor must

by

Recommended calibration points are listed in Table

$1

RD

*+00900.OU

is

calibrated.

To start the calibration, disable the cold junction

setting

bit

may

resistor

of

RTD's

4

in byte

now

for

it

3

of

the setup data with the Setup (SU)

be calibrated using a known input voltage.

for

a voltage input module. Table

to

repeat the

the setup data.

mounted directly on the module connector

voltage inputs to calibrate the module. Due

may

be necessary to repeat the

be

accurate

TS

command

to

0.01%

9.1.

9.1

to

obtain

for proper

Follow

TS

command

gives

of

the

to

the

9-2

Table 9.1

Calibration

Values
Model
M111X

M112X
M113X
M114X
M121X
M123X
M124X
MI 25X
M131

X

MI

32X

M133X

MI

34X

MI

35x
MI 36X
M137X

MI

38X
M141

X

MI

42X

X

M151
M152X

MI 60X

M161

X

Input

+90rnV
+900mV

Stimulus

+4SV

+9v
+9000pA
+90mA
+900mA

+20mA

+39.13
+41.269mV
+17.816mV
+68.783mV
+17.445rnV
+15.576mV

+10.094mV
+33.442mv

300.00Q

300.0052

25mV
9OmV

I8KHZ

25

Sec

Output

Data

+00090.00

+00900.00

+04500.00

+09000.00
+03000.00
+00090.00
+00900.00

+00020.00

+00700.00

+01000.00

+00350.00

+01000.00
+01500.00
+01500.00
+01500.00
+01982.00

+00558.00

+00547.60

+00025.00
+00090.00

+I

8000.00

+25000.00

OF

+01292.00
+01832.00
+00662.00
+01832.00
+02732.00
+02732.00
+02732.00

+03600.00

+01036.40
+01017.70

9-3

APPENDIX

A

Table

of

ASCII characters

Hexadecimal

A

"@

"A 1

"B

"C

"D

"E

"F

"G

"H

"I

"J

"K

"L
"M

"N

"0

D

0

2

3

4

5
6

7

8

9

10
11

12

13
14
15

"P 16

"Q
"R 18

"S
"T

"U

"V
"W

"X

"Y

"Z

"[

"\

"1

""

A

-

!

I,

#
$

Yo

&

17

19
20
21
22
23
24

25

26
27

28
29

30
31

32

33
34

35

36

37

38

39

(

40

(A) and

(Hex),

Hex

00

01

02
03 00000011

04

05

06 00000110
07 00000111
08 00001000

09

OA 00001010

OB

oc

OD 00001101

OE

OF

10
11 00010001
12 00010010
13 00010011
14 00010100
15 00010101
16 00010110

17 00010111
18 00011000
19 00011001
1A
16 00011011
1c 00011100
1D 00011101
1E 00011110

1F

20

21

22
23 00100011
24 00100f00
25 00100101
26 00100110
27 001001fl
28 00101000

and

Binary.

Binary

00000000
00000001

00000010

00000100

00000101

00001001
00001011

00001100
00001110

00001111
00010000

00011010

00011111
00100000
00100001

00100010

ASCII

their equivalent values in Decimal

Claret

(")

represents Control

D

128 80
129
130
131
132 84
133 85
134 86
135 87
136 88
137 89
138 8A
139 88
140 8C
141 8D

142

143 8F
144 90
145

146

147 93
148 94
149 95
150

151
152 98
153 99
154 9A
155 9B
156 9C
157
158 9E
159 9F
160 A0
161 A1
162
163 A3
164 A4
165 A5
166
167 A7
168 A8

Hex

81

82

83

8E

91

92

96

97

9D

A2

A6

function.

Binary

10000000

10000001
1000001
1000001 1

100001

100001 01

100001 1
100001 1 1
10001

10001 001

10001 01

10001 01

10001 100

10001 101

10001 110

10001111

1001

1001 0001

1001

10010011

1001 01

1001 01 01

10010110

100101 11
1001 1000
1001 1001
1001 101
1001 101 1
10011100
10011101
1 001
1001 11 11
101
101 00001

101

101 0001
101 001
101 001 01
10100110

101

1 01 01

00

000

0000

001

00

1

1 10
00000
0001

00

001 11

000

TABLES

(D),

0

0

0

1

0

0

0

1

1

+

,

-

J

0

1
2
3
4
5
6
7
8
9

<

- -

>

?

0

A

B
C

D

E

F

G

H

I

J

K

L

M

N

0

P

Q

R

S

T

U

v

41
42
43
44
45
46
47
48
49
50
51
52

53

54

55

56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

71
72

73
74
75
76
77
78
79
80
81
82
83
84

85

86

29 00101001
2A 00101010
2B 00101011
2c 00101100
2D 00101101
2E 00101110
2F 00101111
30 00110000
31 00110001
32 00170010
33 00110011
34 00110100
35 001101oi
36 00110110
37 00110111
38 00111000
39 00111001
3A 00111010
3B 00111011

3c

3D 00111101

3E

3F

40
41 01000001
42 01000010
43 01000011
44 01000100
45 01000101

46

47 01000111
48 01001000
49 01001001
4A 01001010
4B 01001011
4c 01001100

4D

4E 01001110
4F 01001111

50

51 01010001

52

53 01010011
54 01010100
55 01010101
56 01010110

00111100
00111110

00111111

01000000

01000110

01001101

01010000

01010010

169 A9

170
171
172
173 AD
174
175
176
177 B1
178
179 B3
180 B4
181 65

I82

183 B7
184 B8
185 B9
186
187

188
189
190
191
192

193 C1

194 C2

195 C3

196 C4

197 C5

198 C6

199 c7

200 C8

201 c9

202

203

204 CC

205

206

207

208 DO

209

210 D2

211

212 D4

213

214

AA

A8

AC

AE

AF

BO

62

B6

BA

BB

BC

8D

8E

8F

CO

CA

CB

CD

CE

CF

D1

D3

D5

D6

101 01 001
101 01
101 0101 1
10101100
10101101
101 01
101 01

107 10000
101 10001
101 10010
101 1001 1

1

101 10101
10110110
101 101 11

1011iooo
101
101 11 010

101

101

101
101
101 11 11 1
1

1

1

1

1

11000101

110001 10

11000111

1

11 001 001

11 001 010

1100101

11001 100

11001 101

11001 110

11001 11

1

11 01 0001

11 01 0010

1

1

11010101

11

010

1

10

11

0

1 1

01

00

11

001

1101
11

100

11

101

11

110

1000000
1000001
100001
100001 1
10001

1001

101

101 001
101 01

0101 10

0

00

000

0000

00

1

1

1

1

1

W

X

Y

Z

[

\

1

A

-

a

b

C

d

e

f

g

h

i

j

k

I

m
n

0

P

4

r

S

t

U

V
W
X

Y

z

{

I

1

u

87

88

89
90
91

92

93

94 5E 01011110
95 5F 01011111
96 60 01100000
97 61 01100001

98

99

100 64 01100100
101 65 01100101
102 66 01100110

103 67 01100111

104 68 01101000

105

106
107

108

109 6D 01101101

110 6E 01101110
111 6F 01101111
112 70 01110000

113 71 01110001

114 72 01110010

115 73 01110011

116 74 01110100

117 75 01110101
118 76 01110110

119
120
121 79 01111001
122 7A 01111010
123
124 7C 01111100
125 7D 01111101
126 7E 01111110
127 7F 01111111

57

58

59 01011001

5A

58

5C

5D

62 01100010
63 01100011

69 01101001

6A

6B

6C

77

78 01111000

76

01010111
01011000

01011010
01011011
01011100

01011101

01101010
01101011
01101100

01110111

01111011

215
216 D8 11011000
217
218

219

220

221

222

223

224

225
226

227

228

229 E5

230

231
232

233

234
235
236
237
238 EE 11101170
239

240

241
242
243 F3 11110011
244
245 F5 11110101

246

247 F7 11110111
248 F8 11111000
249

250

251 F8 1111f011
252
253
254

255

D7

D9

DA 11011010
DB 11011011

DC

DD

DE

DF

EO 11100000
El
E2 11100010

E3

E4 11100100

ES

E7
E8

E9

EA

EB 11101011

EC

ED 11101101

EF

FO

F1

F2

F4 11110100
F6 11110110

F9 11111001
FA 11111010

FC 11111100
FD 11111101

FE

FF

11010111
11011001

iioiiioo

11011101
11011110
11011111

11100001

11100011
11100101

11100110
11100111
11101000
11101001

11101010

11101100

11101111
11110000

11110001
11110010

11111110
11111111

A-3

APPENDIX

B

SPECIFICATIONS: (Typical

RTD Types:
Resolution:

Accuracy: k 0.3"

Input connections: 2,3, or 4 wire
Excitation current:
Max. Lead resistance:
Input protection

Automatic linearization and lead compensation

User selectable "C or OF
Lead resistance effect: 3 wire

SENSOR HOOKUPS

The

diagrams to insure proper operation.

=.00385,

0.1O

to

120 Vac

RTD

sensor must be connected as shown in the accompaning

0.25

65Q

4 wire Negligible

@I

.00392

mA

25%,

100

2.5OC

V+

@

per

=

0°C

0

of

+15V)

imbalance

M1400

DATA

SHEET

3-WIRE - The

operation.
coonected
for proper lead compensation. The
together

compensation, the RTD 314 wire set-up bit must be 0 (see Set-Up

command). A typical set-up for 3-wire operation would

M1400

Connect the

to

the

at

the connector with a short wire jumper. For proper 3-wire lead

RTD

J3

Figure

modules are shipped from the factory configured for 3-wire

+I

and

1.

Three-Wire

RTD

-I

sensor as shown

terminals should be matched in length and gauged

+I

and +SENSE terminals must be tied

RTD

Conneckon.

in

the diagram. The wires

be

31

070182.

(SU)

4-WIRE - For 4-wire operation, connect the sensor as shown in the diagram.
the RTD
the

+I
set to 1
would be 31

and

is

equipped with heavy excitation wires, they should be connected to

-I

terminals.

(see

Set-Up (SU) command).

071

182.

For

proper 4-wire operation, the RTD set-up bit

A typical set-up

for

must

4-wire operation

If

be

r

lead

RTD

$y

'

lead

+SENSE

I

2-WIRE

shown in the diagram. This connection provides no lead compensation.
RTD set-up bit

START-UP:

scanned and filtered
errors

this error, wire the sensor should to

error may

-

The 2-wire connection requires two jumpers

if

the RTD sensor is connected while the

also

Figure

can

Figure

During normal operation, the

be eliminated by performing a Remote Reset (RR) command.

be

RTD

J1,

2.

Four-Wire

set

to

J2

=

WIRE

3.

Two-Wire

by

the

RTD

Connection.

either 0 or 1 for this connection.

"'

+SENSE

JUMPER

RTD

MI400

\

Connection.

RTD

module.

the

connector before power is applied. The

lead

This

may

M1400

resistance is periodically

is

on

the connector as

result in large initial

powered up.

To

The

avoid

LEAD

output data is set to

SENSOR GROUNDING: The sensor input is electrically isolated from the power

and communications inputs for common-mode voltages up to 500V.
sensor is to be grounded or shielded, the ground connection should be made to

the

RESISTANCE OVERLOAD:

+99999.99.

-I

terminal for best performance.

If

the lead resistance exceeds

65a,

If

the

the

APPENDIX

C

M1500

The MI500 Bridge Sensor Interface
conditioning functions necessary to interface Strain Gage and other resisitive

bridge devices to an
excitation, an instrumentation amplifier, and a smart analog to digital converter
to convert resistive bridge sensor signals

The user should become familiar with the generic

in the

below.

DATA

The

For Example:

D1000

FORMAT

ASCII

output

Command:

User's Manual before attempting any of the procedures outlined

Response:

In this

case,

the output data is

RS-232C

data

is expressed in millivolts with

$1

RD

*+00012.34

or

12.34

RS-485

(Read

millivolts.

Modules

computer

lo

ASCII

Data)

contain all

port.

data.

D1000

10

microvolt resolution.

DATA SHEET

of

the signal

Each module contains

information described

Modules that are configured for
Modules configured for

overhead

SETUP DATA
The factory setup for all versions of

SENSOR

See Figure 1 for the proper bridge sensor connections. Shields or grounds
should be connected

OFFSET

The MI500 modules do not provide any means of trimming the

the sensor bridge. However, sensor offsets may be nulled from the output data

with the Trim Zero (TZ) command. This method of trimming

because the offset may be trimmed through

time. There is no need to have access to the module since the trimming is

performed remotely.

is

used

to

CONNECTIONS

TRIM

f100

trim

any bridge offsets.

to

the -Excitation terminal.

f

30

mV and have a usable span of

mV have a usable span of

M1500

modules is 31

the

communications port

0701

k

120

mV. The extra

C2

analog

is

f:

60

mV.

offset

convenient

at

of

any

The input signal conditioning circuitry of the

MI500

range to accommodate large sensor offsets without
Modules rated for

specified for

f

100

f

30

rnV

Figuw

mV.

have

I.

Eridgr

have an input

an

input

range

Circuit

Win'ng

range

of

120

capability

mV.

modules have a wide input

the

need for external trims.

of

k

kxc

IE

+IN

PUT

-IN

PUT

+EXCITE

60 mV.

Modules

To

perform an initial offset trim, attach the bridge unit

fig.

1).

Clear out any previous offset trims with
Apply the desired zero condition to the bridge sensor.
this

would

condition could include any tare weight due
attachments that would affect the

the

Read Data

be

the

(RD)

relaxed

or

unstrained condition.

zero

balance. Obtain an initial reading using

command. The output

to

data

to

the module

the

Clear Zero

For

a

Strain Gage Bridge

For

load cells, the zero

a

weighing platform or other

(as

(CZ)

command.

will indicate the total offset
the system. Subtract the offset value from the usable input range
module, either %33mV
overhead".

If

the overhead is not sufficient for your application,

be trimmed externally to lower the offset to

may

be trimmed with a small series resistance
appropriate leg of the bridge
acceptable, the offset may be trimmed with the

or

k120mV. The result is the maximum usable "input

the

bridge must

an

acceptable value. The bridge

or

a

large shunt resistance to the

(as

shown

is

Fig.

Trim

2).

Zero

If

the initial offset is

(TZ)

command.

shown in

of

of

your

c-2

ShuntTtirn

-1

/

kXCITE

tIN

PUT

-INPUT

EXCITE

L

1

Figure

Example

A

load cell to be used in a weighing application
The load
excitation. However, in this particular application, the

tension

The
Clear any

1

:

cell

is rated fur 3 mVN, which

so

its ideal output will be from 0 to

load

cell

is

mounted in its final position with the weighing attachments.

offset

Command:

Response:

Command:

Response:

data that may be stored in the

2.

$IWE

$1

CZ

BridgeCircuitTrim

(CZ

is

(Clear

is

mated to

results

+30

write-protected)

in

a

mV.

M152l

maximum

module:

Zero)

\

a

MI521

k30

mV with

load

cell is used only in

module.

10

V

Verify that the

Command:

Response:

Obtain an initial offset reading from the load

Command:

Response:

The initial offset
After subtracting the

Zero

Trim is cleared:

$1

RZ

*+OOOOO.OO

$1

RD

*+00002.34

is

+2.34

offset

(Read

(Read

mV.

The

the "input overhead"

Zero)

Data)

MI521

cell

with no weight attached:

has

a

useful

is

input range

-62.34

mV

and

of

k60

+57.66

rnV.
rnV.

c-3

The expected
range and

To

Trim Zero:

no

0

to

+30 mV output

external trimming is necessary.

of

the

load

cell easily falls within the overhead

Command:

Response:

Command:

$1

WE

*

$1TZ

(TZ

is

+OOOOO.OO

write protected)

(zero

is

Response:

Now

read the data output to verify the trim:

Command:
Response:

The load cell system has been trimmed to zero.

Example

A

strain gage bridge will be used
strains on a structural member. The bridge is attached
the ideal output from the bridge

2:

$I

RD

*+OOOOO.OO

isk30

(Read

Data)

to

measure both compression

mV full scale.

the

to

desired

a

M1521

output)

and

tensile

module and

Clear the Zero Trim:

Command:
Response:

Command:

Response:

Measure the initial offset from the bridge:

Command:

Response:

In

this case, the bridge exhibits
value from
overhead value
overhead
bridge. The bridge must be trimmed externally

f30mV.

the

is

not large enough

It

is

not

$1

WE

*

$1

CZ

*

$1

RD

*-00043.21

SO

mV useful range of the MI521

of

-16.79

necessary

(Clear Zero)

a large initial offset

mV to

to

to

obtain an exact zero with the external trim.

103.21

cover the

rnV.

-30

mV that may be obtained from the

of

-43.21mV. Subtract this

to

obtain and "input

In this case the -16.79 mV

to

bring the offset to within

c-4

~~

After the external trim has been performed, check the offset:

Command:
Response:

This value
for

the strain gage bridge.

The remaining offset may be trimmed out with the

is

within the

Command:
Response:

Command:
Response:

The bridge is now trimmed to zero.

Verify:

Command:
Response:

$1

RD

*-00022.22

&30

rnV

$1

WE

*

$1

TZ

+OOOOO.OO

*

$1

RD

*

+OOOOU.OO

offset necessary to provide enough headroom

Trim

Zero

(TZ)

command:

The Trim Zero
due to temperature, residual stress, tare, etc.

(TZ)

command

may be used

at

any time to balance out offsets

Excitation

MI500

excitation current available is
with bridges that have input impedances

120

with

UP.

The actual excitation voltage may vary
and
the actual excitation voltage and provides compensation
the nominal value. This results in a constant data output

load even

voltage will appear to be exactly

modules may be ordered with either

60

mA. Modules with

Q

strain gages may be used with

350

i2

+5

resistors. Modules with

V.

However, the module's internal microprocessor constantly monitors

if

the excitation changes. From a user's point

+10

5

V

V

5

V

or

I0

V

10

V

excitation may be used

of

166

ohms

10

V

excitation

excitation will source bridges of

3.5

V

from the nominal values of

or

+5

V.

or

greater. Half-bridges of

if

the bridge

excitation. Maximum

is

completed

85

L2

and

+lo

for

any deviation from

for a constant

of

view, the excitation

bridge

V

c-5

CALIBRATION

Since the

M1500

modules use a ratiometric technique

to

compensate for
variances in the excitation voltage, special consideration is required to properly
calibrate the unit. Figure 3 shows

(DVM)

The voltage source must

must be capable

of

measuring the excitation voltage to 4 digit accuracy.

be

microvolts. The resistive divider may

value from

100

to

1000

R.

The resistor divider places the voltage source in the

center of the common-mode range

350

+

R

the calibration setup. The Digital Voltmeter

able to provide millivolt signals accurate to

be

constructed from

of

the input amplifier

1%

resistors

for

best accuracy.

kxc

ITE

+IN

PUT

-IN

PUT

EXCITE

of

f

5

equal

Step
Step

Step

Step

Step

C-6

1

:

power

2:

set

up

the unit under test and let

the voltage source

to

0

volts

it

warm up for

(short).

at

least

Perform a TZ+OOOOO.OO (Trim

Zero) command to eliminate any common-mode offset errors.

3:

measure the excitation voltage with the

the nominal excitation voltage , either

"compensation factor"

4:

calculate the correct calibration voitage to apply to the unit.

For

f

30

rnV

units the voltage

For

f

100

mV

units

Set the voltage source

5:

trim the unit with the Trim

=

the

CF

is

V

voltage

to

the calculated voltage

Span

is

(TS)

V

DVM.

10

V

=

+50

mV

=

+I

00

command.

Divide the result

or 5 V , to obtain

X

CF

mV X CF

V.

two

a

minutes.

by

For

f

30

mV modules the command

f

100

For

Step

6:

verify the

either

Calibration Example:

We

wish

to calibrate a M1511

30

mV

input.

Step

1

is

straightforward and needs no further explanation.

Step

2:

set the voltage source to 0 volts.

mV modules the command is

trim

*+00050.00

using the

or

*+00100.00

is

$1

TS+00050.00

$1

TS+00100.00

$1

RD

command. The result should be

module. This unit contains 5 V excitation

Trim

zero:

and

a

5

Step

Step

Step

Command:

Response:

Command:

Response:

3:

measure the excitation voltage with the DVM.

measured voltage is 4.954
CF

=

4.954 I 5

4:

calculate the calibration voltage:

V

=

+

50

Set the voltage standard

5:

perform the

Command:

Response:

$1

WE

*

$1

TZ+OOOOO.OO

*

=

.9908

mV X -9908

Trim

Span command:

$1

WE

*

V

Calculate the "compensation factor:

= + 49.54 mV.

to

+

49.54 mV

In

this example the

Step

Command:

Response:

6:

verify

Command:

Response:

$1

TS+00050.00

the calibration, continuing

$1

RD

*+00050.00

to

apply

+

49-54 mV to the

input:

c-7

The span trim is now complete. The Trim Zero (TZ) command may be used

trim sensor offsets without affecting the span trim.

0

PTl

ONS

:

Digital Output:

All MI500 units come standard with a Digital input / Event Counter input. This
connector pin may be factory configured for a Digital

Consult factory.

Output

/

Low

Alarm

to

output.

Continuous Output:

Any of the

continuous output data without interrogation from the host. This option is
for use with
specify continuous output, add
example.

Programmable

The Metrabyte

M1500

by the
as

pounds, psi, Newtons, etc. Non-linear functions may also
into the module.
programmed any number

Bridge

For

convenience, standard bridge completion resistors may

Metrabyte. Standard values available are

DlOOO

series except that the input/output transfer function may be programmed

user.

Output data

Completion

sensor input modules may

LED

display panels

a

"C"

Scaling:

D2500

All

series of interface modules are bridge units similar to the

may

be

scaled to any desired engineering units such

scaling data is stored in non-volatile memory and

of

times. Call factory for details.

Resistors:

be

factory configured

to

provide a continuous visual output. To

suffix

to

the model number;

be

to

MI51

programmed

may

be

obtained from

120

SZ

and

350

Q.

provide

ideal

1C

for

be re-

c-8

APPENDIX

D

The

M1601/2

be

used

in a variety

conditioning.

+fN

HYSTR

+2.W

+2.W

-

-

Frequency Input

of

applications.

I

npu

,

t

Input

Protection

Protection

1M

Hysteresis

Control

II

M1600

modules feature a versatile input stage that can

Fig.

1

is

a block diagram

-.-

DATA

of

the input signal

lsolati on

Isolation

SHEET

Output

Output

to

UP

to

UP

GND
GND

4

Figure

The input
protection is provided to withstand inputs up to 230Vac.

is then fed through an
and formatting.
communications lines. The isolation allows up to
voltage between the input ground and the power connections.

The input comparator employs hysteresis to provide reliable readings with noisy

or

slow input signals. The amount

connecting the hysteresis control

through

1.

M1601/ 2 hput

signal

an external resistor. Fig.

is applied

opta-isolator

The input section is completely isolated from the power and

Signal

to

a precision cornparator through

Conditioning

to

line

(HYSTR)

2 shows

Block

the

module's microprocessor

of

hysteresis

the

most

Diagram.

The comparator output

500V

may

to ground

frequently used connection.

or

the

+

input.

for

of

common-mode

be controlled by

the

2.5V

Input

scaling

terminal

Figure

I

2.

Controlling Hysteresis For Positive-Going Signals

G

This connection

hysteresis

switching levels are

decreases with resulting switching levels

from

Fig.

2

R

is

f

5mV

shows

For

Vhysteresis

R

(in

is

used

centered around

+3V

to

f

0.5V

the relationship between the hysteresis

for

and

+2V,

may

be obtained

unipolar positive-going

a

+2,5V

or

2.5V k 0.5V.

/

2.5V

KQ)

=

34

0.5

switching

of

2.5V

by

selecting

f

5.0mV

>

5mV

Vhysteresis

-

Vhysteresis

and

frequency

level.

If

If:

5mV.

and

If

R

R

is

shorted, the hysteresis

Any hysteresis value

an

appropriate value

I?.

c

0.5V,

signals.

is

left open, the

The

for

R.

D-2

HYSTR

\

~

The input comparator may be setup
the connections in Fig.

Since the input section is isolated, the
signal with a common-mode voltage up to
nected as
+2SV

the switching points appear

signal.

in

Fig.

3,

level. Since the low side

The

hysteresis may

3.

This

the switching points

to

be

be

vaned from k5mv to

for

connection is useful

of

the input signal is connected

symmetrical to zero, as referenced

R

/

R

f;

I

HYSTE

130

OPEN

For

Vhysteresis > 5mV

R

(in

Kh)

Vswitching

comparisons around zero

for

AC

or

+2.5V
500V.

occur

Vswitching

I

pin may
With the hysteresis control

symetrically

M.5V

2.5V

f

0.W

be

connected

on

either side

to

as

shown in Fig.

k

Vhysteresis

and

=

34

Vhysteresis

0.5

-

Vhysteresis

=

2.5

-

14

volts

bipolar

the

to

<

0.5V,

by using

signals.

to

any

con-

of

+2SV

pin,

the input

2.

the

17

+

R

\

Figure

Tine hysteresis control may also be connected to ground

produces another

the

HYSTR

f5mV

To
coupled by simply placing a capacitor in series with the

module contains an internal
biasing.

of

measure

terminal is shorted

hysteresis.

AC

A

.01

uf

3.

Controlling Hysteresis

set

of

switching levels.

to

GND

signals super-imposed

cap

may

IMR

be

used for frequencies

resistor

For

Bipolar Signals.

This connection is shown

the nominal switching

on

a

DC

value,

connected

down

the

+IN

from the

to

10

HZ.

point

input may be

(GND),

is

terminal. The

+IN

to

in

fig.

1.6V

+2.5V

which

4.

with

AC

for

If

D-3

M2000

SERIES

PROGRAMMING

MANUAL

TABLE

OF

CONTENTS

CHAPTER

CHAPTER

CHAPTER

CHAPTER

CHAPTER

2

3

4

1

Linear
Nonlinear Functions

Block

Programming Table 2-2
Breakpoints

Breakpoint Command 3-1

MiNimum

Maimurn Command
Programming

General Guidelines

Function Programming
Linear Scaling

5

Programming

Exam

Scaling

Diagram 2-1

Command

Software

Steps

pies

1-1

1-2

2-5

3-2

3-3

4-1

4-1

4-3

4-4

5-2

5-4

Chapter

1

Introduction

The MetraByte

many difficult interfacing problems that cannot be performed with existing standard interfaces.
The

M2000

standard sensors or to scale the outputs

The

M2000

The

M2000

interfaces
M2000

M2111

case

made
described in the

The
performed through the communications port

to open the module case. Modules may be re-ranged remotely as many times

Function data

Linear

modules operate in the same manner as their

shipped from the factory contains the same transfer function as a M1111

they are both

to

program a M2000,

M2000

Scaling

M2000

series may be programmed to create custom transfer functions to interface to non-

series

series is similar

allow

custom input-to-output transfer functions.

contains built-in commands to create custom functions.

is

stored in nonvolatile memory to retain the scaling even

series of intelligent analog-to-computer interfaces

to

any engineering units desired.

is

an

enhancement of the MetraByte M1000 series of standard interfaces.

to

the

M1000

series in every respect except that the

M1000

tl00

Ml

000

mV inputs and communicate with

you must first be familiar with the operation

manual.

of

the

M2000

module. There is never any need

are

designed to solve

M2000

As

shipped from the factory, the

counterparts. For example, a

module: in this

RS-232C.

Before any attempt

of

a

M1

000

module as

All

programming is

as

desired.

if

power

is

removed.

is

The

basic concept of the

units that may

host computer. In
readings in easy-to-understand engineering units.
might

or an unprogrammed

provide

Pressure

be

instantly read and interpreted without any

fact,

a

1

to

fes

0

500

1000

The

standard output

faithfully output the sensor voltage, the real parameter

M2000

the

5V.

linear output

M2131

il

of

the

series

M2000

unit the output data would

is

to create interfaces which output data in engineering

interfaces may

for

pressures of 0 to

Sensor OutDut

1v

3v

5v

M2131

reads

out

in units

be

used

For

of

data

conversion necessary

with

adurnb terminal to provide data

example.

1000

look

a

typical

psi.

Using

like this:

M2131
+01000.00

Output

pressure sensor

a

M1131

(mV)

module

+03000.00

+05000.00

millivolts. Even though the

of

inferest is pressure, not voltage, and

M2131

by

a

will

(1-2)

MetraByte

M2D00

Programming

Manual

the voItage readings may be difficult to interpret.

M2t31

In

the same pressure
cylinder of compressed air.
this

may be programmed to output the data in units

Pressu

1000

some cases, the desired output may be more specific to a particular application. Assume that

case

Pressure

0

375

750

0

500

we will

re

(DS

assume

I)

sensor

that

Sensor

Output

1v

3v

5v

is used to measure the "fullness"

The

M2131

if

the cylinder reads

1

2.5

4

could

To

make the output data more readable, the

of

pressure:

M2131

Outwt

(mi)

+ooooo.oo

+00500.00

+01000.00

of

a

pressure vessel, such

be

scaled

750

to

output in units

psi it

is

100%

Output

full:

(%I

of

"percent" and in

+ooooo.oo

+00050.00

+00100.00

as

a

Nonlinear Functions

As

we

have

shown

units

we

desire. However,

to

provide a nonlinear transfer function. This capability may be
engineering units for nonlinear sensors. The
technique

approximate afunction,
may

be

to

programmed into the

with the linear pressure sensor example, the output may be scaled to any

the

real

power

describe nonlinear functions.

as

shown in Figure

of

the

M2000

M2000

Up

1.

Figure 2 shows some

series is that

uses

to

24

linear segments may

M2000.

a

linear

they

may

be

programmed

used

to provide outputs in

piece-wise

of

the variety of cutvesthat

approximation

be

used to

-

Figure

1.

Linear

piece-wise

approximation