Omega Products DIN-100 Installation Manual

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User’s Guide

DIN-100 Series

DIN Rail Mount Digital Transmitters

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DIN-100 SERIES USERS MANUAL

REVISED: 10/2004

Omega Engineering, Inc.
P. O. BOX 4047
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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 as suggestions for possible use of the products and not as explicit
performance in a specific application. Specifications may be subject to
change without notice.

DIN-100 modules are not intrinsically safe devices and should not be used
in an explosive environment unless enclosed in approved explosion-proof
housings.

TABLE OF CONTENTS

Warranty 4
CHAPTER 1 Getting Started

Default Mode 1-1
Quick Hook-Up 1-2

CHAPTER 2 Functional Description

Block Diagram 2-2

CHAPTER 3 Communications

Data Format 3-2
RS-485 3-2
RS-485 Multidrop System 3-3

CHAPTER 4 Command Set

Table of Commands 4-6
User Commands 4-6
Error Messages 4-12

CHAPTER 5 Setup Information and Command

Command Syntax 5-1
Setup Hints 5-10

CHAPTER 6 Digital I/O Function

Digital Outputs 6-1
Digital Inputs 6-2

CHAPTER 7 Power Supply
CHAPTER 8 Troubleshooting
CHAPTER 9 Calibration

CHAPTER 10 Extended Addressing
Appendix A (ASCII TABLE )
Appendix B DIN-160 Data Sheet
Appendix C DIN-140 Data Sheet
Appendix D DIN-150 Data Sheet
Appendix E DIN-100 Specifications
Appendix F Modbus Protocol

2

Chapter 1

Getting Started

Default Mode

All DIN-100 modules contain an EEPROM (Electrically Erasable Program­mable 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 if power is
removed. No batteries are used so it is never necessary to open the module
case.

The EEPROM provides tremendous system flexibility since all of the
module’s 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 of
switches; there is no visual indication of the setup information in the module.
It is impossible to tell just by looking at the module what the baud rate,
address, parity and other settings are. It is difficult to establish communica­tions with a module whose address and baud rate are unknown. To
overcome this, each module has an input pin labeled DEFAULT*. By
connecting this pin to Ground, the module is put in a known communications
setup called Default Mode.

The Default Mode setup is: 300 baud, one start bit, eight data bits, one
stop bit, no parity, any address is recognized.

Grounding the DEFAULT* pin does not change any of the setups stored in
EEPROM. The setup may be read back with the Read Setup (RS) command
to determine all of the setups stored in the module. In Default Mode, all
commands are available.

A module in Default Mode will respond to any address except the six
identified illegal values (NULL, CR, $, #, {, }). A dummy address must be
included in every command for proper responses. The ASCII value of the
module address may be read back with the RS command. An easy way to
determine the address character is to deliberately generate an error
message. The error message outputs the module’s address directly after
the “?” prompt.

Setup information in a module may be changed at will with the SetUp (SU)
command. Baud rate and parity setups may be changed without affecting
the Default values of 300 baud and no parity. When the DEFAULT* pin is
released, the module automatically performs a program reset and config­ures itself to the baud rate and parity stored in the setup information.

The Default Mode is intended to be used with a single module connected to
a terminal or computer for the purpose of identifying and modifying setup

Getting Started 1-2

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

RS-485 Quick Hook-Up

Software is not required to begin using your DIN-100 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 or a computer that acts like a dumb
terminal. Make the connections shown in the quick hook-up drawings,
Figures 1.1 or 1.2. Put the module in the default mode by grounding the
Default* terminal. Initialize the terminal communications package on your
computer to put it into the “terminal” mode. Since this step varies from
computer to computer, refer to your 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. The temperature reading is scaled in °C which has been
preset at the factory. Once you have a response from the module you can
turn to the Chapter 4 and get familiar with the command set.

All modules are shipped from the factory with a setup that includes a channel
address of 1, 300 baud rate, no linefeeds, no parity, alarms off, no echo and
two-character delay. Refer to the Chapter 5 to configure the module to your
application.

Figure 1.1 RS-485 Quick Hook-Up.

Getting Started 1-3

RS-485 Quick Hook-up to a RS-232 port

An RS-485 module may be easily interfaced to an RS-232C terminal for
evaluation purposes. This connection is only suitable for benchtop operation
and should never be used for a permanent installation. Figure 1.2 shows the
hook-up. This connection will work provided the RS-232C transmit output is
current limited to less than 50mA and the RS-232C receive threshold is
greater than 0V. All terminals that use 1488 and 1489 style interface IC’s will
satisfy this requirement. With this connection, characters generated by the
terminal will be echoed back. To avoid double characters, the local echo on
the terminal should be turned off.

If the current limiting capability of the RS-232C output is uncertain, insert a
100Ω to 1kΩ resistor in series with the RS-232 output.

In some rare cases it may be necessary to connect the module’s DATA
pin to ground through a 100Ω to 1kΩ resistor.

Figure 1.2 RS-485 Quick Hook-Up with RS-232C Port.

Chapter 2

Functional Description

A functional diagram of a typical module is shown in Figure 2.1. It is a useful
reference that shows the data path in the module and to explain the function
of many of the module’s commands.

The first step is to acquire the sensor signal and convert it to digital data. In
Figure 2.1, all the signal conditioning circuitry has been lumped into one
block, the analog/digital converter (A/D). Autozero and autocalibration is
performed internally and is transparent to the user.

The full-scale output of the A/D converter may be trimmed using the Trim
Span (TS) command. The TS command adjusts calibration values stored
internally in the EEPROM. The TS command should only be used to trim the
accuracy of the unit with a laboratory standard reference applied to the
sensor input.

The trimmed data flows into either of two digital filters. The filter selection is
performed automatically by the microprocessor after every A/D conversion.
The filter selection depends on the difference of the current A/D output data
and the previous data stored in the output data register. If the least significant
decimal digit from the A/D differs from the old output data by more than 10
counts, the large signal filter is selected. If the change is less than 10 counts,
the small signal filter is used.

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 small input changes to give a stable steady-state
output. The large-signal filter is activated by step changes or very noisy input
signals. The time constants for the two filters can be specified independently
with the SetUp (SU) command. The filter values are stored in nonvolatile
memory. Typically, the small-signal filter is set to a larger time constant than
the large-signal filter. This gives very good noise rejection along with fast
response to step inputs.

The scaled data is summed with data stored in the Output Offset Register
to obtain the final output value. The output offset is controlled by the user and
has many purposes. The data in the Output Offset Register may be used to
trim any offsets caused by the input sensor. It may be used to null out
undesired signal such as a tare weight. The Trim Zero (TZ) command is used
to adjust the output to any desired value by loading the appropriate value in
the offset register. The offset register data is nonvolatile.

The value stored in the offset register may be read back using the Read Zero
(RZ) command. Data loaded in with the SP command will be read back with
the sign changed. The output register may be reset to zero with the Clear
Zero (CZ) command.

Functional Description 2-2

The output data may be read with the Read Data (RD) command. In some
cases when a computer is used as a host, the same data value may be read
back several times before it is updated with a new A/D conversion.

The DIN-170 general-purpose digital outputs are open-collector transistor
switches that may be controlled by the host with the Digital Output (DO)
command. They are designed to activate external solid-state relays to
control AC or DC power circuits. The output may also be used to interface
to other logic-level devices. The number of digital outputs available depends
on the module type.

The DIN-170 Digital Input (DI) command is used to sense the logic levels on
the digital input pins DI0-DI7. The digital inputs are used to read logic levels
generated by other devices. They are also useful to sense the state of
electro-mechanical limit switches. The number of digital inputs available
varies with the module type.

Figure 2.1 Analog Input Block Diagram.

Chapter 3

Communications

Introduction

The DIN-100 modules has been carefully designed to be easy to interface
to all popular computers and terminals. All communications to and from the
modules are performed with printable ASCII characters. This allows the
information to be processed with string functions common to most high-level
languages such as BASIC. The ASCII format makes system debugging
easy with a dumb terminal.

This system allows multiple modules to be connected to a communications
port with a single 4-wire cable. Up to 32 RS-485 modules may be strung
together on one cable; 122 with repeaters. The modules communicate with
the host on a polling system; that is, each module responds to its own unique
address and must be interrogated by the host. A module can never initiate
a communications sequence. A simple command/response protocol must
be strictly observed to avoid communications collisions and data errors.

Communications to the DIN-100 modules is performed with two-character
or three-character ASCII command codes such as RD to Read Data from
the analog input. A complete description of all commands is given in the
Chapter 4. A typical command/response sequence would look like this:

Command: $1RD
Response: *+00123.00

A command/response 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 valid response can be in one of three forms:

1) a normal response indicated by a ‘ * ‘ prompt

2) an error message indicated by a ‘ ? ‘ prompt

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 to
the host. Each command has an associated delay time in which the module
is busy calculating the response. If the host does not receive a response in
an appropriate amount of time specified in Table 3.1, a communications
time-out error has occurred. After the communications time-out it is as­sumed that no response data is forthcoming. This error usually results when
an improper command prompt or address is transmitted. The table below
lists the timeout specification for each command:

Communications 3-2

Mnemonic Timeout
DI,DO,RD 10 mS

All other commands 100 mS
Table 3.1 Response Timeout Specifications.
The timeout specification is the turn-around time from the receipt of a

command to when the module starts to transmit a response.

Data Format
All modules communicate in standard NRZ asynchronous data for­mat. This format provides one start bit, seven data bits, one parity bit
and one stop bit for each character.

Single Module Connection

Figure 1.1 shows the connections necessary to attach one module to a host.
Use the Default Mode to enter the desired address, baud rate, and other
setups (see Setups).

RS-485

The RS-485 communications standard satisfies the need for multidropped
systems that can communicate at high data rates over long distances. RS­485 is similar to RS-422 in that it uses a balanced differential pair of wires
switching from 0 to 5V to communicate data. RS-485 receivers can handle
common mode voltages from -7V to +12V without loss of data, making them
ideal for transmission over great distances. RS-485 differs from RS-422 by
using one balanced pair of wires for both transmitting and receiving. Since
an RS-485 system cannot transmit and receive at the same time it is
inherently a half-duplex system. RS-485 offers many advantages over RS­232C:

1) balanced line gives excellent noise immunity

2) can communicate with D1000 modules at 115200 baud

3) communications distances up to 4,000 feet.

4) true multidrop; modules are connected in parallel

5) can disconnect modules without losing communications

6) up to 32 modules on one line; 122 with repeaters

7) no communications delay due to multiple modules

8) simplified wiring using standard telephone cable

RS-485 does have disadvantages. Very few computers or terminals have
built-in support for this new standard. Interface boards are available for the
IBM PC and compatibles. As RS-485 system usually requires an interface.

The DIN-190 will convert RS-232 signals to RS-485 or repeat RS-485
signals. The DIN-190 connected as an RS-485 repeater can be used to

Communications 3-3

extend an existing RS-485 network or connect up to 122 modules on one
serial communications port.

RS-485 Multidrop System

Figure 3.1 illustrates the wiring required for multiple-module RS-485 sys­tem. Notice that every module has a direct connection to the host system.
Any number of modules may be unplugged without affecting the remaining
modules. Each module must be setup with a unique address and the
addresses can be in any order. All RS-485 modules must be setup for no
echo to avoid bus conflicts (see Setup). Also note that the connector pins on
each module are labelled with notations (B), (R), (G), and (Y). This
designates the colors used on standard 4-wire telephone cable:

Label Color
(B) GND Black

(R) V+ Red
(G) DATA* (-) Green
(Y) DATA (+) Yellow

This color convention is used to simplify installation. If standard 4-wire
telephone cable is used, it is only necessary to match the labeled pins with
the wire color to guarantee correct installation.

DATA* on the label is the complement of DATA (negative true).
To minimize unwanted reflections on the transmission line, the bus should

be arranged as a line going from one module to the next. ‘Tree’ or random
structures of the transmission line should be avoided. When using long
transmission lines and/or high baud rates, the data lines should be termi­nated at each end with 200 ohm resistors. Standard values of 180 ohms or
220 ohms are acceptable.

During normal operation, there are periods of time where all RS-485 drivers
are off and the communications lines are in an 'idle' high impedance
condition. During this condition, the lines are susceptible to noise pickup
which may be interpreted as random characters on the communications
line. To prevent noise pickup, all RS-485 systems should incorporate 1K
ohm bias resistors as shown in Figure 3.1. The resistors will maintain the
data lines in a 'mark' condition when all drivers are off.

DIN-191 and DIN-192 modules have the 1KΩ resistors built-in.
Special care must be taken with very long busses (greater than 1000 feet)

to 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 ‘#’

Communications 3-4

form of all 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 GND wire is used both as a power
connection and the common reference for the transmission line receivers in
the modules. Voltage drops in the GND leads appear as a common-mode
voltage to the receivers. The receivers are rated for a maximum of -7V. of
common-mode voltage. For reliable operation, the common mode voltage
should be kept below -5V.

To avoid problems with voltage drops, modules may be powered locally
rather than transmitting the power from the host. Inexpensive 'calculator'
type power supplies are useful in remote locations. When local supplies are
used, be sure to provide a ground reference with a third wire to the host or
through a good earth ground. With local supplies and an earth ground, only
two wires for the data connections are necessary.

Communications Delay

All DIN-100 modules are setup at the factory to provide two units of
communications delay after a command has been received (see Chapter 5).
This delay is necessary when using host computers that transmit a 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. If the host computer transmits a carriage return as
a single character, the delay may be set to zero to improve communications
response time.

Communications 3-5

Chapter 4

ASCII Command Set

The DIN-100 modules operate with a simple command/response protocol
to control all module functions. A command must be transmitted to the
module by the host computer or terminal before the module will respond with
useful data. A module can never initiate a communications sequence. A
variety of commands exists to exploit the full functionality of the modules. A
list of available commands and a sample format for each command is listed
in Table 4.1.

Command Structure

Each command message from the host must begin with a command prompt
character to signal to the modules that a command message is to follow.
There are two valid prompt characters; a dollar sign character ($) is used to
generate a short response message from the module. A short response is
the minimum amount of data necessary to complete the command. The
second prompt character is the pound sign character (#) which generates
long responses (will be covered later in this chapter).

The prompt character must be followed by a single address character
identifying the module to which the command is directed. Each module
attached to a common communications port must be setup with its own
unique address so that commands may be directed to the proper unit.
Module addresses are assigned by the user with the SetUp (SU) command.
Printable ASCII characters such as ‘1’ (ASCII $31) or ‘A’ (ASCII $41) are the
best choices for address characters.

The address character is followed by a two-character command that
identifies the function to be performed by the module. All of the available
commands are listed in Table 4.1 along with a short function definition. All
commands are described in Chapter 4. Commands must be transmitted as
upper-case characters.

A two-character checksum may be appended to any command message as
a user option. See ‘Checksum’ in Chapter 4 .

All commands must be terminated by a Carriage Return character (ASCII
$0D). (In all command examples in this text the Carriage Return is either
implied or denoted by the symbol ‘CR’.)

Data Structure

Many commands require additional data values to complete the command
definition as shown in the example commands in Table 4.1. The particular
data necessary for these commands is described in full in the complete
command descriptions.

Command Set 4-2

The most common type of data used in commands and responses is analog
data. Analog data is always represented in the same format for all models
in the DIN-100 series. Analog data is represented as a nine-character string
consisting of a sign, five digits, decimal point, and two additional digits. The
string represents a decimal value in engineering units. Examples:

+12345.68
+00100.00

-00072.10

-00000.00

When using commands that require analog data as an argument, the full
nine-character string must be used, even if some digits are not significant.
Failure to do this results in a SYNTAX ERROR.

Analog data responses from the module will always be transmitted in the
nine-character format. This greatly simplifies software parsing routines
since all analog data is in the same format for all module types.

In many cases, some of the digits in the analog data may not be significant.
For instance, the DIN-130 thermocouple input modules feature 1 degree
output resolution. A typical analog data value from this type of module could
be +00123.00. The two digits to the right of the decimal point have no
significance in this particular model. However, the data format is always
adhered to in order to maintain compatibility with other module types.

The maximum computational resolution of the module is 16 bits, which is
less than the resolution that may be represented by an analog data variable.

The Digital Input, Digital Output, and Setup commands use hexadecimal
representations of data. The data structures for these commands are
detailed in the command descriptions.

Write Protection

Many of the commands listed in Table 4.1 are under the heading of ‘Write
Protected Commands’. These commands are used to alter setup data in the
module’s EEPROM. They are write protected to guard against accidental
loss of setup data. All write-protected commands must be preceded by a
Write Enable (WE) command before the protected command may be
executed.

Miscellaneous Protocol Notes

The address character must transmitted immediately after the command
prompt character. After the address character the module will ignore any
character below ASCII $23 (except CR). This allows the use of spaces
(ASCII $20) within the command message for better readability if desired.

Command Set 4-3

The length of a command message is limited to 20 printable characters. If
a properly addressed module receives a command message of more than
20 characters the module will abort the whole command sequence and no
response will result.

If a properly addressed module receives a second command prompt before
it receives a CR, the command will be aborted and no response will result.

Response Structure

Response messages from the module begin with either an asterisk ‘ * ‘
(ASCII $2A) or a question mark ‘ ? ‘ (ASCII $3F) prompt. The ‘ * ‘ prompt
indicates acknowledgment of a valid command. The ‘ ? ‘ prompt precedes
an error message. All response messages are terminated with a CR. Many
commands simply return a ‘ * ‘ character to acknowledge that the command
has been executed by the module. Other commands send data information
following the ‘ * ‘ prompt. The response format of all commands may be found
in the detailed command description.

The maximum response message length is 20 characters.
A command/response 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 valid response can be in one of three forms:

1) a normal response indicated by a ‘ * ‘ prompt

2) an error message indicated by a ‘ ? ‘ prompt

3) a communications time-out error

When a module receives a valid command, it must interpret the command,
perform the desired function, and the communicate the response back to the
host. Each command has an associated delay time in which the module is
busy calculating the response. If the host does not receive a response in an
appropriate amount of time specified in Table 4.1, a communications time­out error has occurred. After the communications time-out it is assumed that
no response data is forthcoming. This error usually results when an
improper command prompt or address is transmitted.

Long Form Responses

When the pound sign ‘ # ‘ command prompt is used, the module responds
with a ‘long form’ response. This type of response will echo the command
message, supply the necessary response data and will add a two-character
checksum to the end of the message. Long form responses are used when
the host wishes to verify the command received by the module. The
checksum is included to verify the integrity of the response data. The ‘ # ‘
command prompt may be used with any command. For example:

Command Set 4-4

Command: $1RD (short form)
Response: *+00072.10

Command: #1RD (long form)
Response: *1RD+00072.10A4 (A4=checksum)

Checksum

Checksum is a two character hexadecimal value appended to the end of a
message. It verifies that the message received is exactly the same as the
message sent. The checksum ensures the integrity of the information
communicated.

Command Checksum

A two-character checksum may be appended to any command to the
module as a user option. When a module interprets a command, it looks for
the two extra characters and assumes that it is a checksum. If the checksum
is not present, the module will perform the command normally. If the two
extra characters are present, the module calculates the checksum for the
message. If the calculated checksum does not agree with the transmitted
checksum, the module responds with a ‘BAD CHECKSUM’ error message
and the command is aborted. If the checksums agree, the command is
executed. If the module receives a single extra character, it responds with
‘SYNTAX ERROR’ and the command is aborted For example:

Command: $1RD (no checksum)
Response: *+00072.10

Command: $1RDEB (with checksum)
Response: *+00072.10

Command: $1RDAB (incorrect checksum)
Response: ?1 BAD CHECKSUM

Command: $1RDE (one extra character)
Response: ?1 SYNTAX ERROR

Response Checksums

If the long form ‘ # ‘ version of a command is transmitted to a module, a
checksum will be appended to the end of the response. For example:

Command: $1RD (short form)
Response: *+00072.10

Command: #1RD (long form)
Response: *1RD+00072.10A4 (A4=checksum)

Command Set 4-5

Checksum Calculation

The checksum is calculated by summing the hexadecimal values of all the
ASCII characters in the message. The lowest order two hex digits of the sum
are used as the checksum. These two digits are then converted to their
ASCII character equivalents and appended to the message. This ensures
that the checksum is in the form of printable characters.

Example: Append a checksum to the command #1DOFF

Characters: # 1 D O F F
ASCII hex values: 23 31 44 4F 46 46
Sum (hex addition) 23 + 31 + 44 + 4F + 46 + 46 = 173

The checksum is 73 (hex). Append the characters 7 and 3 to the end of
the message: #1DOFF73

Example: Verify the checksum of a module response *1RD+00072.10A4

The checksum is the two characters preceding the CR: A4
Add the remaining character values:
*1RD+00072. 10

2A + 31 + 52 + 44 + 2B + 30 + 30 + 30 + 37 + 32 + 2E + 31 + 30 = A4

The two lowest-order hex digits of the sum are A4 which agrees with the
transmitted checksum.

The transmitted checksum is the character string equivalent to the calcu­lated hex integer. The variables must be converted to like types in the host
software to determine equivalency.

If checksums do not agree, a communications error has occurred.
If a module is setup to provide linefeeds, the linefeed characters are not

included in the checksum calculation.
Parity bits are never included in the checksum calculation.

Command Set 4-6

Table 4.1 DIN-100 Command Set

Command and Definition Typical Typical

Command Response
Message Message

($ prompt)

DI Read Alarms/Digital Inputs $1DI *0003
DO Set Digital Outputs $1DOFF *
RD Read Data $1RD *+00072.00
RS Read Setup $1RS *31070142
RZ Read Zero $1RZ *+00000.00
WE Write Enable $1WE *

Write Protected Commands
MBR Set Modbus Address $1MBR01 *

MBD Modbus Disable $1MBD *
RR Remote Reset $1RR *
SU Setup Module $1SU31070142 *
TS Trim Span $1TS+00600.00 *
TZ Trim Zero $1TZ+00000.00 *

DIN-100 User Commands

Note that in all command and response examples given below, a carriage
return is implied after every character string.

Clear Zero (CZ)

The Clear Zero command clears the output offset register value to
+00000.00. This command clears any data resulting from a Trim Zero (TZ).

Command: $1CZ
Response: *

Command: #1CZ
Response: *1CZF8

Digital Input (DI)

The DI command reads the status of the digital inputs on the DIN-171. The
response to the DI command is four hex characters representing two bytes
of data. The second byte contains the digital input data.

Command: $1DI
Response: *0003

Command: #1DI
Response: *1DI0003AB

Command Set 4-7

The second byte displays the hex value of the digital input status. The
number of digital inputs varies depending on module type.

Digital Inputs DI5 DI4 DI3 DI2 DI1 DI0
Data Bits 543210

For example: A typical response from a $1DI command could be: *00FE.
This response indicates that DI0 = 0 and all other digital inputs are = 1

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 Output (DO)
The DO command controls eight bits of digital outputs on the DIN-172
module connector. The number of digital outputs implemented depends on
the model used. The digital outputs allow the module to control external
circuits under host command. The DO command requires an argument of
two hex characters specifying the eight bits of output data.

Digital Outputs DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
Data Bits 76543210

The electrical implementation of the digital output consists of open-collector
transistors wired to the module connector. If a digital output is set to ‘1’ the
corresponding transistor is turned on and sinks current. Note that when a
digital output bit is set to ‘1’ the electrical output is near 0 volts. If a digital
output is set to ‘0’ the corresponding transistor is turned off and sinks no
current.

Assume a module has two digital outputs, and you wish to turn both outputs
on (sinking current). Set data bit 0 and data bit 1 to ‘1’. Since the module has
only two digital outputs, all the other bits are ‘don’t cares’. For example, this
command will turn both outputs ‘on’:

Command: $1DOFF
Response: *

To turn both outputs off you could use the command:

Command: $1DO00
Response: *

Command Set 4-8

Digital output settings are not stored in nonvolatile memory. If a power failure
occurs, all digital outputs will be 0 upon power up.

The DO command is the only means of changing digital outputs. There is no
software provision to read the state of digital outputs.

Read Data (RD)

The read data command is the basic command used to read the buffered
sensor data. The output buffer (Figure 2.1) allows the data to be read
immediately without waiting for an input A/D conversion. For example:

Command: $1RD
Response: *+00072.00

Command: #1RD
Response: *1RD+00072.10A4

Since the RD command is the most frequently used command in normal
operation, a special shortened version of the command is available. If a
module is addressed without a two-letter command, the module interprets
the string as an RD command.

Command: $1
Response: *+00072.10

Command: #1
Response: *1RD+00072.10A4

Remote Reset (RR)

The reset command allows the host to perform a program reset on the
module’s microprocessor. This may be necessary if the module’s internal
program is disrupted by static or other electrical disturbances. Once a reset
command is received, the module will recalibrate itself. The calibration
process takes approximately 3 seconds. For example:

Command: $1RR
Response: *

Command: #1RR
Response: *1RRFF

In general, the state of the digital outputs and the event counter will not be
affected by the RR command. However, if data in the microprocessor’s RAM
(Random Access Memory) has been lost, the RR command will result in a
full power-up reset.

Any commands sent to the module during the self-calibration sequence will
result in a NOT READY error.

Command Set 4-9

Read Setup (RS)

The read setup command reads back the setup information loaded into
the module’s nonvolatile memory with the SetUp (SU) command. The
response to the RS command is four bytes of information formatted as
eight hex characters.

Command: $1RS
Response: *31070142

Command: #1RS
Response: *1RS3107014292

The response contains the module’s channel address, baud rate and
other parameters. Refer to the setup command (SU), and Chapter 5 for
a list of parameters in the setup information.

When reading the setup with a checksum, be sure not to confuse the
checksum with the setup information.

Read Zero (RZ)

The Read Zero command reads back the value stored in the Output
Offset Register (Figure 2.1).

Command: $1RZ
Response: *+00000.00

Command: #1RZ
Response: *1RZ+00000.00B0

The data read back from the Output Offset Register may be interpreted
in several ways. The commands that affect this value are: Trim Zero
(TZ) and Clear Zero (CZ).

Setup Command (SU)

Each DIN-100 module contains an EEPROM (Electrically Erasable
Programmable Read Only Memory) which is used to store module
setup information such as address, baud rate, parity, etc. The
EEPROM is a special type of memory that will retain information even
if power is removed from the module. The EEPROM is used to replace
the usual array of DIP switches normally used to configure electronic
equipment.

The SetUp command is used to modify the user-specified parameters
contained in the EEPROM to tailor the module to your application.
Since the SetUp command is so important to the proper operation of
a module, a whole section of this manual has been devoted to its
description. See Chapter 5.

Command Set 4-10

The SU command requires an argument of eight hexadecimal digits to
describe four bytes of setup information:

Command: $1SU31070182
Response: *

Command: #1SU31070182
Response: *1SU3107018299

Trim Span (TS)

The trim span command is the basic means of trimming the accuracy of a
DIN-100 module. The TS command loads a calibration factor into nonvola­tile memory to trim the full-scale output of the signal conditioning circuitry.
It is intended only to compensate for long-term drifts due to aging of the
analog circuits, and has a useful trim value of ±10% of the nominal
calibration set at the factory. It is not to be used to change the basic transfer
function of the module. Full information on the use of the TS command may
be found in Chapter 9.

Command: $1TS+00500.00
Response: *

Command: #1TS+00500.00
Response: *1TS+00500.00B0

Caution! TS is the only command associated with the span trim. There is no

provision to read back or clear errors loaded by the TS command. Misuse
of the TS command may destroy the calibration of the unit which can only
be restored by using laboratory calibration instruments in a controlled
environment. An input signal must be applied when using this command.

Trim Zero (TZ)

The Trim Zero command is used to load a value into the Output Offset
Register (Figure 2.1) to null out an offset in the output data. It may be used
to trim offsets created by sensors. It may also be used to null out data to
create a deviation output.

Example: Assume a DIN-151 bridge input module is being used with a load
cell for weight measurement. An initial reading of the load cell with no weight
applied may reveal an initial offset error:

Command: $1RD
Response: *+00005.00

With no weight applied, trim the output to read zero. To trim, use the TZ
command and specify the desired output reading:

Command: $1TZ+00000.00 (zero output)
Response: *

Command Set 4-11

With no weight applied, trim the output to read zero. To trim, use the TZ
command and specify the desired output reading:

Command: $1TZ+00000.00 (zero output)
Response: *

The TZ command will load a data value into the Output Offset Register to
force the output to read zero. The module will compensate for any previous
value loaded into the Output Offset Register. If another output reading is
taken, it will show that the offset has been eliminated:

Command: $1RD
Response: *+00000.00

Although the TZ command is most commonly used to null an output to zero,
it may be used to offset the output to any specified value. Assume that with
the previously nulled load cell system we performed this command:

Command: $1TZ-00100.00
Response: *

The new data output with no load applied would be:

Command: $1RD
Response: *-00100.00

The load cell output is now offset by -100.
The offset value stored by the TZ command is stored in nonvolatile memory

and may be read back with the Read Zero (RZ) command and cleared with
the Clear Zero (CZ) command.

The SetPoint (SP) command will write over any value loaded by the TZ
command.

Write Enable (WE)

Each module is write protected against accidental changing of alarms,
limits, setup, or span and zero trims. To change any of these write protected
parameters, the WE command must precede the write-protected command.
The response to the WE command is an asterisk indicating that the module
is ready to accept a write-protected command. After the write-protected
command is successfully completed, the module becomes automatically
write disabled. Each write-protected command must be preceded individu­ally with a WE command. For example:

Command: $1WE
Response: *

Command: #1WE
Response: *1WEF7

Command Set 4-12

If a module is write enabled and the execution of a command results in an
error message other than WRITE PROTECTED, the module will remain
write enabled until a command is successfully completed resulting in an ‘ *
‘ prompt. This allows the user to correct the command error without having
to execute another WE command.

Write Extended Address (WEA)

ERROR MESSAGES
The DIN-100 modules feature extensive error checking on input commands

to avoid erroneous operation. Any errors detected will result in an error
message and the command will be aborted.

All error messages begin with “?”, followed by the channel address, a space
and error description. The error messages have the same format for either
the ‘ $ ‘ or ‘ # ‘ prompts. For example:

?1 SYNTAX ERROR

There are eight error messages, and each error message begins with a
different character. It is easy for a computer program to identify the error
without having to read the entire string.

ADDRESS ERROR
There are six ASCII values that are illegal for use as a module address:

NULL ($00), CR ($0D), $ ($24), # ($23), { ($7B) and } ($7D). The ADDRESS
ERROR will occur when an attempt is made to load an illegal address into
a module with the SetUp (SU) command. An attempt to load an address
greater than $7F will produce an error.

BAD CHECKSUM
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 error is due to
noise or interference on the communications line. Often, repeating the
command solves the problem. If the error persists, either the checksum is
calculated incorrectly or there is a problem with the communications
channel. More reliable transmissions might be obtained by using a lower
baud rate.

Command Set 4-13

COMMAND ERROR
This error occurs when the two-character command is not recognized by the

module. Often this error results when the command is sent with lower-case
letters. All valid commands are upper-case.

NOT READY
If a module is reset, it performs a self-calibration routine which takes 2-3

seconds to complete. Any commands sent to the module during the self­calibration period will result in a NOT READY error. When this occurs, simply
wait a couple seconds and repeat the command.

The module may be reset in three ways: a power-up reset, a Remote Reset
(RR) command, or an internal reset. All modules contain a ‘watchdog’ timer
to ensure proper operation of the microprocessor. The timer may be tripped
if the microprocessor is executing its program improperly due to power
transients or static discharge.

If the NOT READY error persists for more than 30 seconds, check the power
supply to be sure it is within specifications.

PARITY ERROR
A parity error can only occur if the module is setup with parity on (see Setup).

Usually a parity error results from a bit error caused by interference on the
communications line. Random parity errors are usually overcome by simply
repeating the command. If too many errors occur, the communications
channel may have to be improved or a slower baud rate may be used.

A consistent parity error will result if the host parity does not match the
module parity. In this situation, the easiest solution may be to change the
parity in the host to obtain communication. At this point the parity in the
module may be changed to the desired value with the SetUp (SU) command.

The parity may be changed or turned off by using Default Mode.
SYNTAX ERROR
A SYNTAX ERROR will result if the structure of the command is not correct.

This is caused by having too few or too many characters, signs or decimal
points missing or in the wrong place. Table 4.1 lists the correct syntax for
all the commands.

VALUE ERROR
This error results when an incorrect character is used as a numerical value.

Data values can only contain decimal digits 0-9. Hex values used in the
SetUp (SU) and Digital Output (DO) commands can range from 0-F.

Command Set 4-14

WRITE PROTECTED
All commands that write data into nonvolatile memory are write-protected to

prevent accidental erasures. These commands must be preceded with a
Write Enable (WE) command or else a WRITE PROTECTED error will
result.

Chapter 5

Setup Information/SetUp Command

The DIN-100 modules feature a wide choice of user configurable options
which gives them the flexibility to operate on virtually any computer or
terminal based system. The user options include a choice of baud rate,
parity, address, and many other parameters. The particular choice of
options for a module is referred to as the setup information.

The setup information is loaded into the module using the SetUp (SU)
command. The SU command stores 4 bytes (32 bits) of setup information
into a nonvolatile memory contained in the module. Once the information is
stored, the module can be powered down indefinitely (10 years minimum)
without losing the setup data. The nonvolatile memory is implemented with
EEPROM so there are no batteries to replace.

The EEPROM has many advantages over DIP switches or jumpers normally
used for option selection. The module never has to be opened because all
of the options are selected through the communications port. This allows the
setup to be changed at any time even though the module may be located
thousands of feet away from the host computer or terminal. The setup
information stored in a module may be read back at any time using the Read
Setup command (RS).

The following options can be specified by the SetUp command:
Channel address (122 values)

Linefeeds
Parity (odd, even, none)
Baud rate (300 to 38,400)
Addressing Mode: Extended/Normal
CJC disable (DIN-130 series)
RTD 3/4 wire (DIN-140 series)
Communication delay (0-6 characters)
Number of displayed digits
Large-signal filter constant
Small-signal filter constant

Each of these options will be described in detail below. For a quick look-up
chart on all options, refer to Tables 5.1-4.

Command Syntax

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

$1SU[byte1][byte 2][byte 3][byte 4]

Setup & SetUp Command 5-2
A typical SetUp command would look like: $1SU31070182.
Notice that each byte is represented by its two-character ASCII equivalent.

In this example, byte 1 is described by the ASCII characters ‘31’ which is the
equivalent of binary 0011 0001 (31 hex). The operand of a SU command
must contain exactly 8 hex (0-F) characters. Any deviation from this format
will result in a SYNTAX ERROR. The Appendix contains a convenient hex­to-binary conversion chart.

For the purposes of describing the SetUp command, ‘bit 7’ refers to the
highest-order bit of a byte of data. ‘Bit 0’ refers to lowest-order bit:

‘bit number’: 7 6 5 43210
binary data: 0 0 1 10001 = $31 (hex)

The SU command is write protected to guard against erroneous changes in
the setup data; therefore each SU command must be preceded by a Write
Enable (WE) command. To abort an SU command in progress, simply send
a non-hex character (an ‘X’ for example) to generate a SYNTAX ERROR,
and try again.

CAUTION: Care must be exercised in using the SU command. Improper use

may result in changing communications parameters (address, baud rate,
parity) which will result in a loss of communications between the host and
the module. In some cases the user may have to resort to using Default
Mode to restore the proper setups. The recommended procedure is to first
use the Read Setup (RS) command to to examine the existing setup data
before proceeding with the SU command.

Byte 1

Byte 1 contains the module (channel) address. The address is stored as the
ASCII code for the string character used to address the module. In our
example command $1SU31070080 , the first byte ‘31’ is the ASCII code for
the character ‘1’. If our sample command is sent to a module, the EEPROM
will be loaded with the address ‘1’, which in this particular case remains
unchanged. To change the module address to ‘2’ , byte 1 of the SetUp
command becomes ‘32’, which is the ASCII code for the character ‘2’. Now
the command will look like this: $1SU32070080. When this command is
sent, the module address is changed from ‘1’ to ‘2’ and will no longer respond
to address ‘1’.

When using the SU command to change the address of a module, be sure
to record the new address in a place that is easily retrievable. The only way
to communicate with a module with an unknown address is with the Default
Mode.

Setup & SetUp Command 5-3

are six ASCII codes that are illegal for use as an address. These codes are
$00, $0D, $24, $23, $7B, $7D which are ASCII codes for the characters
NUL, CR, $, #, { and }. Using these codes for an address will cause an
ADDRESS ERROR and the setup data will remain unchanged. This leaves
a total of 122 possible addresses that can be loaded with the SU command.
It is highly recommended that only ASCII codes for printable characters be
used ($21 to $7E) which greatly simplifies system debugging with a dumb
terminal. Refer to Appendix A for a list of ASCII codes. Table 5.1 lists the
printable ASCII codes that may be used as addresses.

Table 5.1 Byte 1 ASCII Printable Characters.

HEX ASCII HEX ASCII HEX ASCII HEX ASCII
21 ! 3A : 51 Q 68 h

22 “ 3B ; 52 R 69 i
25 % 3C < 53 S 6A j
26 & 3D = 54 T 6B k
27 ‘ 3E > 55 U 6C l
28 ( 3F ? 56 V 6D m
29 ) 40 @ 57 W 6E n
2A * 41 A 58 X 6F o
2B+ 42B 59Y 70p
2C , 43 C 5A Z 71 q
2D - 44 D 5B [ 72 r
2E . 45 E 5C \ 73 s
2F/ 46F 5D] 74t
300 47G 5E^ 75u
31 1 48 H 5F _ 76 v
32 2 49 I 60 ‘ 77 w
33 3 4A J 61 a 78 x
34 4 4B K 62 b 79 y
35 5 4C L 63 c 7A z
36 6 4D M 64 d 7B {
37 7 4E N 65 e 7C |
38 8 4F O 66 f 7D }
39 9 50 P 67 g 7E ~

Setup & SetUp Command 5-4
Byte 2

Byte 2 is used to configure some of the characteristics of the communica­tions channel; linefeeds, parity, and baud rate.

Linefeeds

The most significant bit of byte 2 (bit 7) controls linefeed generation by the
module. This option can be useful when using the module with a dumb
terminal. All responses from the DIN-100 are terminated with a carriage
return (ASCII $0D). Most terminals will generate a automatic linefeed when
a carriage return is detected. However, for terminals that do not have this
capability, the D1000 module can generate the linefeed if desired. By setting
bit 7 to ‘1’ the module will send a linefeed (ASCII $0A) before and after each
response. If bit 7 is cleared (0), no linefeeds are transmitted.

When using the ‘#’ command prompt, the linefeed characters are not
included in the checksum calculation.

Parity

Bits 5 and 6 select the parity to be used by the module. Bit 5 turns the parity
on and off. If bit 5 is ‘0’, the parity of the command string is ignored and the
parity bit of characters transmitted by the module is set to ‘1’.

If bit 5 is ‘1’, the parity of command strings is checked and the parity of
characters output by the module is calculated as specified by bit 6.

If bit 6 is ‘0’, parity is even; if bit 6 is ‘1’, parity is odd.
If a parity error is detected by the module, it will respond with a PARITY

ERROR message. This is usually caused by noise on the communications
line.

If parity setup values are changed with the SU command, the response to
the SU command will be transmitted with the old parity setup. The new parity
setup becomes effective immediately after the response message from the
SU command.

Baud Rate

Bits 0-3 specify the communications baud rate. The baud rate can be
selected from ten values between 300 and 38400 baud. Refer to Table 5.2
for the desired code.

The baud rate selection is the only setup data that is not implemented
directly after an SU command. In order for the baud rate to be actually
changed, a module reset must occur. A reset is performed by sending a
Remote Reset (RR) command (see Communications) or powering down.
This extra level of write protection is necessary to ensure that communica­tions to the module is not accidently lost. This is very important when

Setup & SetUp Command 5-5
changing the baud rate of an RS-485 string. For more information on

changing baud rate, refer to Chapter 3.
Let’s run through an example of changing the baud rate. Assume our sample

module contains the setup data value of ‘31070080’. Byte 2 is ‘07’. By
referring to the SU command chart we can determine that the module is set
for no linefeeds, no parity, and baud rate 300. If we perform the Read Setup
command with this module we would get:

Command: $1RS
Response: *31070080

Let’s say we wish to change the baud rate to 9600 baud. The code for 9600
baud is ‘0010’ (from Table 5.2). This would change byte 2 to ‘02’. To perform
the SU command we must first send a Write Enable command because SU
is write protected:

Command: $1WE
Response: *

Command: $1SU31020080
Response: *

This sequence of messages is done in 300 baud because that was the
original baud rate of the module. The module remains in 300 baud after this
sequence. We can use the Read Setup (RS) command to check the setup
data:

Command: $1RS
Response: *31020080

Notice that although the module is communicating in 300 baud, the setup
data indicates a baud rate of 9600 (byte 2 = ‘02’). To actually change the
baud rate to 9600, send a Remote Reset (RR) command (RR is write
protected):

Command: $1WE
Response: *

Command: $1RR
Response: *

Up to this point all communications have been sent at 300 baud. The module
will not respond to any further communications at 300 baud because it is now
running at 9600 baud. At this point the host computer or terminal must be set
to 9600 baud to continue operation.

If the module does not respond to the new baud rate, most likely the setup
data is incorrect. Try various baud rates from the host until the module
responds. The last resort is to set the module to Default Mode where the

Setup & SetUp Command 5-6
baud rate is always 300.

Bit 4

Bit 4 is used to enable or disable extended addressing mode.

Table 5.2 Byte 2: Linefeed, Parity, Addressing and Baud Rate.

FUNCTION DATA BIT

76543210
LINEFEED 1
NO LINEFEED 0
NO PARITY 0 0
NO PARITY 1 0
EVEN PARITY 0 1
ODD PARITY 1 1
NORMAL ADDRESSING 0
EXTENDED ADDRESSING 1
38400 BAUD 0000
19200 BAUD 0001
9600 BAUD 0010
4800 BAUD 0011
2400 BAUD 0100
1200 BAUD 0101
600 BAUD 0110
300 BAUD 0111

Byte 3

This byte contains the setup information for several seldom-used options.
The default value for this byte is ‘01’.

Disable CJC
RTD 3/4 Wire
Trigger Edge Select

The setup information stored in bit 4 has different meanings depending on
the DIN-100 model number.

Disable CJC; this function pertains only to the DIN-130 series of thermo­couple input modules. If the bit is set to ‘1’ the Cold Junction Compensation
is disabled. The module calculates the temperature output with a fixed cold
junction temperature of 0 degrees Celsius. This setup is useful for calibrating
the module or in cases where remote CJC is used. Normally this bit is cleared
to ‘0’.

Setup & SetUp Command 5-7

RTD 3/4 Wire; this function pertains only to the DIN-140 series of RTD input
modules. If the bit is set to ‘1’, the module provides the correct lead­compensation calculation for 4-wire RTD’s. If the bit is cleared to ‘0’, the
module calculates the correct lead compensation for 3-wire RTD’s. Meas­urement errors may result if the module is not set to the correct sensor type.
This function has no affect on DIN-145 or DIN-146 Thermistor inputs.

Delay

Bits 0 and 1 specify a minimum turn-around delay between a command and
the module response. This delay time is useful on host systems that are not
fast enough to capture data from quick-responding commands such as RD.
This is particularly true for systems that use software UART’s. The specified
delay is added to the typical command delays listed in the Software
Considerations section of Chapter 3. Each unit of delay specified by bits 0
and 1 is equal to the amount of time required to transmit one character with
the baud rate specified in byte 2. For example, one unit of delay at 300 baud
is 33.3 mS; for 38.4 kilobaud the delay is 0.26 mS. The number of delay units
is selectable from 0 to 6 as shown in Table 5.3.

In some systems, such as IBM BASIC, a carriage return (CR) is always
followed by a linefeed (LF). The DIN-100 modules will respond immediately
after a command terminated by a CR and will ignore the linefeed. To avoid
a communications collision between the linefeed and the module response,
the module should be setup to delay by 2 units.

Table 5.3 Byte 3 Options.

FUNCTION DATA BIT

76543210

CJC ( DIN-130’S ) 0
NO CJC ( DIN-130’S ) 1
3 WIRE ( DIN-140’S ) 0
4 WIRE ( DIN-140’S ) 1
NO DELAYS 0 0
2 BYTE TIME DELAYS 0 1
4 BYTE TIME DELAYS 1 0
6 BYTE TIME DELAYS 1 1

Setup & SetUp Command 5-8

Byte 4

This setup byte specifies the number of displayed digits and the digital filter
time constants.

Number of displayed digits

For ease of use, the data outputs of all modules are standardized to a
common 7-digit output consisting of sign, 5 digits, decimal point, and two
more digits. Typical output data looks like: +00100.00. However, best-case
resolution of the A/D converter is 1 part in 32,768. In some cases, the
resolution of the output format is much greater than the resolution of the
measurement system. In such cases, the trailing digits of the response
would 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 7 Bit 6
0 0 XXXX0.00 (4 displayed digits)

0 1 XXXXX.00 (5 displayed digits)
1 0 XXXXX.X0 (6 displayed digits)
1 1 XXXXX.XX (7 displayed digits)

For example, the DIN-141 model for RTD’s has 0.1 degree output resolution.
The appropriate number of digits for this module is 6, to mask off the 0.01
digit which has no meaningful data. In some cases, the user may want to limit
the output resolution to 1 degree. To do this, select bits 6 and 7 to display
5 digits. With this selection, the right-most two digits will always be set to ‘0’.

The number of displayed digits affects only data received from an RD or ND
command.

Large Signal Filter, Bits 3,4,5
Small Signal Filter, Bits 0,1,2

The modules contain a versatile single-pole, low-pass digital filter to smooth
out unwanted noise caused by interference or small signal variations. The
digital filter offers many advantages over traditional analog filters. The
filtering action is done completely in firmware and is not affected by
component drifts, offsets, and circuit noise typically found in analog filters.
The filter time constant is programmable through the SetUp (SU) command
and can be changed at any time, even if the module is remote from the host.

The digital filter features separate time constants for large and small signal
variations. The Large Signal Filter time constant is controlled by bits 3,4,5.
This time constant is used when large signal variations are present on the
input. The Small Signal Filter time constant is controlled by bits 0,1,2. This
filter time constant is automatically selected when input signal variations are
small. The microprocessor in the module automatically selects the correct

Setup & SetUp Command 5-9

filter constant after every A/D conversion. The constant selected depends
on the magnitude of the change of the input signal and the setup for the
number of digits displayed. The microprocessor always keeps the value of
the last calculated output to compare to a new data conversion. If the new
data differs from the last output by more than ten counts of the last displayed
digit, the large signal time constant is used in the digital filter. If the result of
the most recent A/D conversion differs from the last output value by less than
ten counts of the last displayed digit, the small signal time constant is used.
Let’s look at an example:

The DIN-141 RTD module has a standard output resolution of 0.1 degrees.
The standard number-of-displayed-digits setup for this module is 6 digits,
from byte 4 of the setup data. Therefore, the large signal filter will be selected
if a new input conversion differs from the previous value by > 1.0 degree:

Previous data New data Filter selected
+00100.00 +00100.50 small
+00100.00 +00101.50 large
+00100.00 +00099.90 small
+00100.00 +00098.90 large

-00050.50 -00050.00 small

-00050.50 -00060.00 small

If the number of displayed digits is changed to reduce output resolution, filter
selection is also affected. If the number of displayed digits in the previous
example is changed to 5, the output resolution becomes 1.0 degree.

In this case the large signal time constant is used if the new reading differs
from the old by more than 10.0 degrees:

Previous data New data Filter selected
+00100.00 +00105.00 small
+00100.00 +00111.00 large
+00100.00 +00091.00 small
+00100.00 +00085.00 large

-00050.00 -00045.00 small

-00050.00 -00039.00 large

Large Signal Time Constant

The large signal filter time constant is specified by bits 3,4,5 of byte 4. It may
be specified from 0 (no filter) to 16 seconds. The time constant for a first­order filter is the time required for the output to reach 63% of its final value
for a step input.

Setup & SetUp Command 5-10

Small Signal Time Constant

Bits 0,1, 2 specify the filter time constant for small signals. Its values are
similar to the ones for the large signal filter. Most sensors can benefit from
a small amount of small signal filtering such as T = 0.5 seconds In most
applications, the small signal time constant should be larger than the large
signal time constant. This gives stable readings for steady-state inputs while
providing fast response to large signal changes.

Table 5.4 Byte 4 Displayed Digits and Filter Time Constants.
BYTE 4

FUNCTION DATA BIT

76543210
+XXXX0.00 DISPLAYED DIGITS 0 0
+XXXXX.00 DISPLAYED DIGITS 0 1
+XXXXX.X0 DISPLAYED DIGITS 1 0
+XXXXX.XX DISPLAYED DIGITS 1 1
NO LARGE SIGNAL FILTERING 0 0 0

0.25 SECOND TIME CONSTANT 0 0 1

0.5 SECOND TIME CONSTANT 0 1 0

1.0 SECOND TIME CONSTANT 0 1 1

2.0 SECOND TIME CONSTANT 1 0 0

4.0 SECOND TIME CONSTANT 1 0 1

8.0 SECOND TIME CONSTANT 1 1 0

16.0 SECOND TIME CONSTANT 1 1 1
NO SMALL SIGNAL FILTERING 0 0 0

0.25 SECOND TIME CONSTANT 0 0 1

0.5 SECOND TIME CONSTANT 0 1 0

1.0 SECOND TIME CONSTANT 0 1 1

2.0 SECOND TIME CONSTANT 1 0 0

4.0 SECOND TIME CONSTANT 1 0 1

8.0 SECOND TIME CONSTANT 1 1 0

16.0 SECOND TIME CONSTANT 1 1 1

Setup Hints

Until you become completely familiar with the SetUp command, the best
method of changing setups is to change one parameter at a time and to verify
that the change has been made correctly. Attempting to modify all the setups
at once can often lead to confusion. If you reach a state of total confusion,
the best recourse is to reload the factory setup shown in Table 5.5 and try
again, changing one parameter at a time. Use the Read Setup (RS)
command to examine the setup information currently in the module as a
basis for creating a new setup.

Setup & SetUp Command 5-11

By using the RS command and changing one setup parameter at a time, any
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 this case, it may be necessary to use
the Default Mode to re-establish communications.

Table 5.5 Factory Setups by Model.

(All modules from the factory are set for address ‘1’, 300 baud, no parity)
DIN-100 Series Model Number Setup Message
111, 115, 125 310701C2

110, 113, 114 31070142
13X 31070142
141, 142, 143 , 112 31070182
145, 15X 310701C2
16X 310701C0
17X 31070100

Chapter 6

Digital I/O Functions

The DIN-100 series features the DIN-171 module with six digital inputs
and the DIN-172 module with six digital outputs .

Digital Outputs

A digital output consists of an open-collector transistor controlled by the
host, using the Digital Output (DO) command (See Figure 6.1). The open­collector configuration is used to provide maximum versatility in interfacing
to solid state relays (SSR’s) or to standard logic levels such as TTL or
CMOS. Each digital output can sink up to 100mA and can withstand up to
30V. Power in the transistor must be limited to 300mW. The emitter of each
transistor is tied to the GND terminal on the input connector.

A typical connection of a digital output is shown in Figure 6.1. In this case, a
solid state relay is controlled by the DIN-172 module. The SSR can then be
used to control AC power to alarms, heaters, pumps, etc. A typical connec­tion to a logic input is shown in Figure 6.2. In some cases, the common­mode voltage of the GND terminal may be significantly different from the
ground potential of the logic input to be interfaced. This may occur when

Figure 6.1 Digital Outputs Used With Relays

the module is powered remotely. In this case, an opto-isolator may be used
to eliminate the common-mode voltage. See Figure 6.2. In all cases, the
current switched by the transistor may not be more than 100mA.

Digital I/O Functions 6-2

If the module loses power, the digital outputs are turned off. The outputs
will remain off until switched by a Digital Output (DO) command.

The digital outputs are not affected by the Remote Reset (RR) command.

Digital Inputs

Digital inputs are used to sense switch closures and the state of digital
signals. The inputs are protected to voltages up to ±30V and are normally
pulled up to the logic “1” condition (see Figure 6.2). Digital inputs can be
read by the Digital Input (DI) command. Voltage inputs less than 1V are
read back as ‘0’. Signals greater than 3.5V are read as ‘1’. No other
commands have any affect on the inputs.

Switch closures can be read by the digital input by simply connecting the
switch between GND terminal and a digital input with the addition of an
external 10K pull-up resistor to +5Vdc. The pull-up supplies only 0.5ma;
therefore, self-wiping switches designed for low current operation should
be used.

Digital inputs may be used to sense AC voltages by using isolated sensing
modules offered by many manufacturers.

Figure 6.2 Typical Digital Input Circuit.

Chapter 7

Power Supply

DIN-100 modules require a regulated +5Vdc power-supply. The modules
contain a low voltage detection circuit that shuts down all circuits in the
module at approximately 4.5 Vdc. All power supply specifications are
referred to the module connector; the effects of line voltage drops must be
considered when the module is powered remotely.

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

The low voltage detection circuit shuts down the module at approximately

4.5Vdc. If the module is interrogated while in a low power supply condition,
the module will not respond. Random NOT READY error messages could
indicate that the power supply voltage is periodically drooping below the

4.7V minimum.
In some cases, a small number of modules may be operated by “stealing”

power from a host computer or terminal.
Small systems may be powered by using wall-mounted calculator-type

modular power supplies. These units are inexpensive and may be obtained
from many retail electronics outlets.

For best reliability, modules operated on long communications lines (>500
feet) should be powered locally using small calculator-type power units. This
eliminates the voltage drops on the Ground lead which may interfere with
communications signals. In this case the V+ terminal is connected only to the
local power supply. The Ground terminal must be connected back to the host
to provide a ground return for the communications loop.

All DIN-100 modules are protected against power supply reversals.

Chapter 8

Troubleshooting

Symptom:
Module is not responding to commands
Module responds with ?1 COMMAND ERROR to every command.
Characters in each response message appear as graphics characters

• RS-485 Module is not responding to commands

1. Using a voltmeter, measure the power supply voltage at the
+Vs and GND terminals to verify the power supply voltage is constantly
5Vdc ± 5%.

2. Verify using an ohmmeter that there are no breaks in the
communications data lines.

3. When using a serial communications converter (DIN-191) ensure that
the communications Baud Rate switch is set to the proper Baud Rate value.

4. Confirm software communications settings in Host computer match
those values being used by the connected module(s).

5. If the Baud Rate value being used in the application is greater than 300
Baud and the module will only communicate 300 Baud then make sure that
the DEFAULT* terminal is not connected to Ground (GND).

6. Ensure that module RS-485 "Data" line (module terminal pin #7) is
connected to the Host RS-485 "Data+" line.

7. Ensure that module RS-485 "Data*" line (module terminal pin #8) is
connected to the Host RS-485 "Data-" line.

8. If the problem is not corrected after completing the steps above then
connect the module by itself to a Host computer as outlined in Chapter 1.0
under "Quick Hook-up". Start the supplied Utility software and please call the
factory for further assistance.

• Module responds with ?1 COMMAND ERROR to every command

Ensure that characters in the command message are uppercase char-

acters. All commands consist of uppercase characters only.

• Characters in each response message appear as graphics characters

1. Set the communications software parity setting to "M" for 'MARK' parity
type and 7 data bits. Or, utilize any parity type in both the module and
software other than "NO" parity.

2. In custom written software routines, mask off the most significant bit of
each received character to logic "0". Thus forcing the received character to
7-bit ASCII value.

Chapter 9

Calibration

The DIN-100 module is initially calibrated at the factory and has a recom­mended calibration interval of one year. Calibration constants are stored in
the EEPROM and may be trimmed using the Trim Span (TS) and Trim Zero
(TZ) commands. Calibration procedure is as follows.

Voltage and current inputs: clear the output offset register using the Clear
Zero (CZ) command. Zero trims are not neccessary due to the built-in auto­zero function. Apply a known calibrated voltage or current to the input of the
module. The calibrated stimulus should be adjusted to be near 90% of the full
scale output of the modules for best results. The accuracy of the calibrated
voltage or current must be better than the rated accuracy of the module,
which in most cases is 0.02% of full scale. Use the Read Data (RD) com­mand to obtain an output reading. If the output corresponds to the applied
input, no calibration is necessary. If the output is in overload, check the
circuit connections or use a different input value to obtain an output within the
operating range of the module.

To trim the output, use the Trim Span (TS) command. The argument of the
TS command should correspond to the desired module output. After per­forming the TS command, verify the trim with the RD command. For example
to trim a DIN-112 module:

1. Clear the output offset register.

Command: $1WE
Response: * (CZ is write protected)

Command: $1CZ
Response: *

2. Apply an input voltage near 90% of rated full scale. In this case we use a
+900mV input voltage accurate to at least 0.02%. Obtain an output reading.

Command: $1RD
Response: *+00900.30

In this case, the output of the module is off by 300µV. To trim:

Command: $1WE
Response: * (TS is write protected)

Command: $1TS+00900.00
Response: *

This sequence will trim the output to +00900.00. Verify:

Command: $1RD
Response: *+00900.00 (The module is calibrated.)

Calibration 9-2

Thermocouples: Disable the cold junction compensation by setting bit 4 in

byte 3 of the setup data with the SetUp (SU) command. The module may
now be calibrated using a known input voltage. Perform the calibration as
described for a voltage input module. Table 9.1 gives recommended calibra­tion points. Due to the nonlinear nature of thermocouples, it may be neces­sary to repeat the TS command to obtain the desired output. After calibration
is complete, enable the cold junction compensation by clearing bit 4 in byte
3 of the setup data.

RTD: Use a calibrated resistor mounted directly on the module connector to
avoid lead resistance errors. The resistor must be accurate to 0.01% for
proper calibration. Recommended calibration points are listed in Table 9.1.
Follow the command sequence described for voltage inputs to calibrate the
module. Due to the nonlinear nature of RTD’s it may be necessary to repeat
the TS command to obtain the desired output.

Table 9.1 Calibration Values
Model Input Stimulus Output Data

DIN-110 +9000µV +09000.00
DIN-111 +90mV +00090.00
DIN-112 +900mV +00900.00
DIN-113 +4.5V +04500.00
DIN-114 +9V +09000.00
DIN-115 +90V +00090.00
DIN-125 +20mA +00020.00
DIN-131 +39.13mV +00700.00
DIN-132 +41.269mV +01000.00
DIN-133 +17.816mV +00350.00
DIN-134 +68.783mV +01000.00
DIN-135 +17.445mV +01500.00
DIN-136 +15.576mV +01500.00
DIN-137 +10.094mV +01500.00
DIN-138 +33.442mV +01982.00
DIN-141 300.00Ω +00558.00
DIN-142 300.00Ω +00547.60
DIN-143 134.91Ω +00115.00
DIN-145 206.1Ω +00090.00
DIN-146 3018Ω +00140.00
DIN-151 25mV +00025.00
DIN-152 25mV +00025.00
DIN-153 90mV +00090.00
DIN-154 90mV +00090.00
DIN-161 18Khz +18000.00

Chapter 10

Extended Addressing

The DIN-100 may be configured to a special command format called
Extended Addressing. This mode uses a different prompt, either '{' or '}'
to distinguish it from the regular command syntax. The major difference
in syntax for the Extended Addressing mode is that it uses a two-charac­ter address. A typical command in Extended Address mode would look
like this:

Command: {01WE
Response: *

Both the command and response are terminated with carriage returns.
Note that the command uses a two-character address, '01.'

There are two benefits to using Extended Addressing with the DIN-100:

1) Greatly expanded addressing capability.

2) Allow for a more structured addressing method in
large systems.

With single-byte addressing of the normal command structure, address
space is limited to 122 points. Extended addressing allows an address­ing range of 249 points.

Structured Addressing

Even for a relatively small system, it can be advantageous to employ a
hierarchical addressing system as used in Fig. 7.1. This is particularly
true in systems that consist of many sites that are identical. From a host
software standpoint, each site can be treated identically with the same
module addresses, with each site having a different DIN-100 address.

Extended Address Syntax

The command syntax used with Extended Addressing is quite similar to
the normal protocol. The Extended Address commands are initiated with
a '{' character (left curly brace, ASCII $7B), or a '}' character (right curly
brace, ASCII $7E). The '{' prompt is analogous to the '$' prompt in that it
returns the shortest possible response to complete the command. The '}'
prompt is similar to the '#' prompt in that the command is echoed and a
checksum is generated along with the other data necessary to complete
the response. The '*' response prompt is used in all command forms.

The Extended Address commands use a two-character ASCII address,
each character may be one of 122 legal possibilities. Illegal characters
are: NULL ($00), CR ($0D), $ ($24), # ($23), { ($7B), and } ($7E).

Command examples with Extended Address '01':

Command: {01WE
Response: *

Command: }01WE
Response: *01WE27

Command: {01RS
Response: *31070000 (typical)

Command: }01RS
Response: *01RS31070000BB (typical)

Checksums may be appended to commands:

Command: {01WE78
Response: *

All commands that are available with single-byte addressing may be
accessed with Extended Addressing, and vice-versa.

Appendix A

ASCII Table

Table of ASCII characters (A) and their equivalent values in Decimal (D),
Hexadecimal (Hex), and Binary. Claret (^) represents Control function.

A D Hex Binary D Hex Binary
^@ 0 00 00000000 128 80 10000000
^A 1 01 00000001 129 81 10000001
^B 2 02 00000010 130 82 10000010
^C 3 03 00000011 131 83 10000011
^D 4 04 00000100 132 84 10000100
^E 5 05 00000101 133 85 10000101
^F 6 06 00000110 134 86 10000110
^G 7 07 00000111 135 87 10000111
^H 8 08 00001000 136 88 10001000
^I 9 09 00001001 137 89 10001001
^J 10 0A 00001010 138 8A 10001010
^K 11 0B 00001011 139 8B 10001011
^L 12 0C 00001100 140 8C 10001100
^M 13 0D 00001101 141 8D 10001101
^N 14 0E 00001110 142 8E 10001110
^O 15 0F 00001111 143 8F 10001111
^P 16 10 00010000 144 90 10010000
^Q 17 11 00010001 145 91 10010001
^R 18 12 00010010 146 92 10010010
^S 19 13 00010011 147 93 10010011
^T 20 14 00010100 148 94 10010100
^U 21 15 00010101 149 95 10010101
^V 22 16 00010110 150 96 10010110
^W 23 17 00010111 151 97 10010111
^X 24 18 00011000 152 98 10011000
^Y 25 19 00011001 153 99 10011001
^Z 26 1A 00011010 154 9A 10011010
^[ 27 1B 00011011 155 9B 10011011
^\ 28 1C 00011100 156 9C 10011100
^] 29 1D 00011101 157 9D 10011101
^^ 30 1E 00011110 158 9E 10011110
^_ 31 1F 00011111 159 9F 10011111

32 20 00100000 160 A0 10100000
! 33 21 00100001 161 A1 10100001
“ 34 22 00100010 162 A2 10100010

ASCII Tables A-2

A D Hex Binary D Hex Binary
# 35 23 00100011 163 A3 10100011
$ 36 24 00100100 164 A4 10100100
% 37 25 00100101 165 A5 10100101
& 38 26 00100110 166 A6 10100110
‘ 39 27 00100111 167 A7 10100111
( 40 28 00101000 168 A8 10101000
) 41 29 00101001 169 A9 10101001
* 42 2A 00101010 170 AA 10101010
+ 43 2B 00101011 171 AB 10101011
, 44 2C 00101100 172 AC 10101100

- 45 2D 00101101 173 AD 10101101
. 46 2E 00101110 174 AE 10101110
/ 47 2F 00101111 175 AF 10101111
0 48 30 00110000 176 B0 10110000
1 49 31 00110001 177 B1 10110001
2 50 32 00110010 178 B2 10110010
3 51 33 00110011 179 B3 10110011
4 52 34 00110100 180 B4 10110100
5 53 35 00110101 181 B5 10110101
6 54 36 00110110 182 B6 10110110
7 55 37 00110111 183 B7 10110111
8 56 38 00111000 184 B8 10111000
9 57 39 00111001 185 B9 10111001
: 58 3A 00111010 186 BA 10111010
; 59 3B 00111011 187 BB 10111011
< 60 3C 00111100 188 BC 10111100
= 61 3D 00111101 189 BD 10111101
> 62 3E 00111110 190 BE 10111110
? 63 3F 00111111 191 BF 10111111
@ 64 40 01000000 192 C0 11000000
A 65 41 01000001 193 C1 11000001
B 66 42 01000010 194 C2 11000010
C 67 43 01000011 195 C3 11000011
D 68 44 01000100 196 C4 11000100
E 69 45 01000101 197 C5 11000101
F 70 46 01000110 198 C6 11000110
G 71 47 01000111 199 C7 11000111
H 72 48 01001000 200 C8 11001000
I 73 49 01001001 201 C9 11001001
J 74 4A 01001010 202 CA 11001010
K 75 4B 01001011 203 CB 11001011

ASCII Tables A-3

A D Hex Binary D Hex Binary
L 76 4C 01001100 204 CC 11001100
M 77 4D 01001101 205 CD 11001101
N 78 4E 01001110 206 CE 11001110
O 79 4F 01001111 207 CF 11001111
P 80 50 01010000 208 D0 11010000
Q 81 51 01010001 209 D1 11010001
R 82 52 01010010 210 D2 11010010
S 83 53 01010011 211 D3 11010011
T 84 54 01010100 212 D4 11010100
U 85 55 01010101 213 D5 11010101
V 86 56 01010110 214 D6 11010110
W 87 57 01010111 215 D7 11010111
X 88 58 01011000 216 D8 11011000
Y 89 59 01011001 217 D9 11011001
Z 90 5A 01011010 218 DA 11011010
[ 91 5B 01011011 219 DB 11011011
\ 92 5C 01011100 220 DC 11011100
] 93 5D 01011101 221 DD 11011101
^ 94 5E 01011110 222 DE 11011110
_ 95 5F 01011111 223 DF 11011111
‘ 96 60 01100000 224 E0 11100000
a 97 61 01100001 225 E1 11100001
b 98 62 01100010 226 E2 11100010
c 99 63 01100011 227 E3 11100011
d 100 64 01100100 228 E4 11100100
e 101 65 01100101 229 E5 11100101
f 102 66 01100110 230 E6 11100110
g 103 67 01100111 231 E7 11100111
h 104 68 01101000 232 E8 11101000
i 105 69 01101001 233 E9 11101001
j 106 6A 01101010 234 EA 11101010
k 107 6B 01101011 235 EB 11101011
l 108 6C 01101100 236 EC 11101100
m 109 6D 01101101 237 ED 11101101
n 110 6E 01101110 238 EE 11101110
o 111 6F 01101111 239 EF 11101111
p 112 70 01110000 240 F0 11110000
q 113 71 01110001 241 F1 11110001
r 114 72 01110010 242 F2 11110010
s 115 73 01110011 243 F3 11110011
t 116 74 01110100 244 F4 11110100

ASCII Tables A-4

A D Hex Binary D Hex Binary
u 117 75 01110101 245 F5 11110101
v 118 76 01110110 246 F6 11110110
w 119 77 01110111 247 F7 11110111
x 120 78 01111000 248 F8 11111000
y 121 79 01111001 249 F9 11111001
z 122 7A 01111010 250 FA 11111010
{ 123 7B 01111011 251 FB 11111011
| 124 7C 01111100 252 FC 11111100
} 125 7D 01111101 253 FD 11111101
~ 126 7E 01111110 254 FE 11111110

127 7F 01111111 255 FF 11111111

Appendix B

DIN-160 Data Sheet

The Frequency Input modules feature a versatile input stage that can be
used in a variety of applications. Figure B-1 is a block diagram of the input
signal conditioning.

Figure B-1. DIN-161 Input Signal Conditioning Block Diagram.

The input signal is applied to a precision comparator through the + Input.
Input protection is provided to withstand inputs up to 230Vac. The compara­tor output is then fed through an opto-isolator to the module’s microproces­sor for scaling and formatting. The input section is completely isolated from
the power and communications lines. The isolation allows up to 500V of
common-mode 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 of hysteresis may be controlled by
connecting the hysteresis control line (HYSTR) to ground or the 2.5V
terminal through an external resistor. Figure 2 shows the most frequently
used connection.

DIN-160 Data Sheet B-3

Figure B-3. Controlling Hysteresis For Bipolar Signals.

Figure B-4. Controlling Switching Level and Hysteresis.

R

Open
ØΩ

For V

hysteresis

V

2.5V ± 0.5V

1.7V ± 5mV

>5mV and <0.5V:

34 V

R (in KΩ) =

0.5 - V

V

switching

= 2.5 -

switching

14

17 + R

± V

hysteresis

hysteresis

hysteresis

The hysteresis control may also be connected to ground (GND), which
produces another set of switching levels. This connection is shown in figure
B-4. If the HYSTR terminal is shorted to GND the nominal switching point is

1.6V with ±5mV of hysteresis.
To measure AC signals super-imposed on a DC value, the input may be AC

coupled by simply placing a capacitor in series with the +IN terminal. The
module contains an internal 1MΩ resistor connected from the +IN to +2.5V
for biasing. A .01 uf cap may be used for frequencies down to 10HZ.

Appendix C

DIN-140 Data Sheet

SPECIFICATIONS: (Typical @ 25°C, V+ = +5V)
RTD Types: =.00385, .00388, .00392 100Ω @ 0°C

Resolution: 0.1°
Accuracy: ±0.3°C
Input connections: 2, 3, or 4 wire
Excitation current: .25 mA
Max. Lead resistance: 50Ω
Input protection to 120Vac
Automatic linearization and lead compensation
Lead resistance effect: 3 wire—2.5°C per Ω of imbalance
4 wire—Negligible

Sensor Hookups

The RTD sensor must be connected as shown in the accompanying
diagrams to insure proper operation.

3-Wire: The DIN-140 modules are shipped from the factory configured for
3-wire operation. Connect the RTD sensor as shown in the diagram. The
wires connected to the +I and -I terminals should be matched in length and
gauged for proper lead compensation. The +I and +SENSE terminals must
be tied together at the connector with a short wire jumper. For proper 3-wire
lead compensation, the RTD 3/4 wire set-up bit must be 0 (see Set-Up (SU)
command). A typical set-up for 3-wire operation would be 31070182.

J3 = Wire Jumper

Figure C-1. 3-wire RTD Configuration

4-Wire: For 4-wire operation, connect the RTD as shown in the diagram. If
the RTD has heavy excitation wires, they should be connected to the +I and

-I terminals. For proper 4-wire operation, the RTD set-up bit must be set to
1 (see Set-Up (SU) command). A typical set-up for 4-wire operation would
be 31071182.

Figure C-2. 4-Wire RTD Configuration.

2-Wire: The 2-wire connection requires two jumpers on the connector (J1
& J2) as shown in the diagram. This connection provides no lead compen­sation. The RTD set-up bit can be either 0 or 1 for this connection.

J1,J2 = Wire Jumper

Figure C-3. 2-Wire RTD Configuration.

Start-Up: During normal operation, the RTD lead resistance is periodically
scanned and filtered by the DIN-140 module. This may result in large initial
errors if the RTD sensor is connected while the DIN-140 is powered up. To
avoid this error, the sensor should be wired to the connector before power
is applied. The error may also be eliminated by performing a Remote Reset
(RR) command.

Lead Resistance Overload: If the lead resistance exceeds 50Ω, the output
data is set to +99999.99.

Sensor Grounding: The sensor input is electrically isolated from the power
and communications inputs for common-mode voltages up to 500V. If the
sensor is to be grounded or shielded, the ground connection should be made
to the -I terminal.

Appendix D

DIN-150 Data Sheet

The DIN-150 Bridge Sensor Interface Modules contain all of the signal
conditioning functions necessary to interface Strain Gage and other resis­tive bridge devices to an RS-485 computer port. Each module contains
excitation, an instrumentation amplifier, and a smart analog to digital
converter to convert resistive bridge sensor signals to ASCII data.

The user should become familiar with the generic DIN-100 information
described in the DIN-100 User’s Manual before attempting any of the
procedures outlined below.

Data Format

The ASCII output data is expressed in millivolts with 10 microvolt resolution.
For Example:

Command: $1RD (Read Data)
Response: *+00012.34

In this case, the output data is 12.34 millivolts.
Modules that are configured for ±30mV and have a usable span of ±60mV.

Modules configured for ±100mV have a usable span of ±120mV. The extra
overhead is used to trim any bridge offsets.

Setup Data

The factory setup for all versions of DIN-150 modules is 310701C2

Sensor Connections

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

Offset Trim

The DIN-150 modules do not provide any means of trimming the analog
offset of the sensor bridge. However, sensor offsets may be nulled from the
output data with the Trim Zero (TZ) command. This method of trimming is
convenient because the offset may be trimmed through the communications
port at any time. There is no need to have access to the module since the
trimming is performed remotely.

The input signal conditioning circuitry of the DIN-150 modules have a wide
input range to accommodate large sensor offsets without the need for
external trims. Modules rated for ±30mV have an input range capability of
±60mV. Modules rated for ±100mV have an input range of ±120mV.

DIN-150 Data Sheet D-2

Figure D-1 Bridge Circuit Wiring

To perform an initial offset trim, attach the bridge unit to the module (as
shown in Figure D-1). Clear out any previous offset trims with the Clear Zero
(CZ) command. Apply the desired zero condition to the bridge sensor. For
a Strain Gage Bridge this would be the relaxed or unstrained condition. For
load cells, the zero condition could include any tare weight due to a weighing
platform or other attachments that would affect the zero balance. Obtain an
initial reading using the Read Data (RD) command. The output data will
indicate the total offset of the system. Subtract the offset value from the
usable input range of your module, either ±60mV or ±120mV. The result is
the maximum usable “input overhead”. If the overhead is not sufficient for
your application, the bridge must be trimmed externally to lower the offset
to an acceptable value. The bridge may be trimmed with a small series
resistance or a large shunt resistance to the appropriate leg of the bridge (as
shown is Figure D-2). If the initial offset is acceptable, the offset may be
trimmed with the Trim Zero (TZ) command.

DIN-150 Data Sheet D-3

Figure D-2 Bridge Circuit Trim

Example 1:
A load cell to be used in a weighing application is mated to a DIN-152
module. The load cell is rated for 3mV/V, which results in a maximum ±30mV
with 10V excitation. However, in this application, the load cell is used only
in tension so its ideal output will be from 0 to +30mV.

The load cell is mounted in position with the weighing attachments. Clear
any offset data that may be stored in the DIN-152 module:

Command: $1WE (CZ is write-protected)
Response: *

Command: $1CZ (Clear Zero)
Response: *

Verify that the Zero Trim is cleared:

Command: $1RZ (Read Zero)
Response: *+00000.00

Obtain an initial offset reading from the load cell with no weight attached:

Command: $1RD (Read Data)
Response: *+00002.34

DIN-150 Data Sheet D-4

The initial offset is +2.34mV. The DIN-152 has a useful input range of
±60mV. After subtracting the offset the “input overhead” is -62.34mV and
+57.66mV. The expected 0 to +30mV output of the load cell easily falls within
the overhead range and no external trimming is necessary.

To Trim Zero:

Command: $1WE (TZ is write protected)
Response: *

Command: $1TZ+00000.00 (zero output)
Response: *

Now read the data output to verify the trim:

Command: $1RD (Read Data)
Response: *+00000.00

The load cell system has been trimmed to zero.
Example 2:

A strain gage bridge will be used to measure both compression and tensile
strains on a structural member. The bridge is attached to a DIN-152 module
and the ideal output from the bridge is ±30mV full scale.

Clear the Zero Trim:

Command: $1WE
Response: *

Command: $1CZ (Clear Zero)
Response: *

Measure the initial offset from the bridge:

Command: $1RD
Response: *-00043.21

In this case, the bridge exhibits a large initial offset of -43.21mV. Subtract this
value from the ±60mV useful range of the DIN-152 to obtain and “input
overhead” value of -16.79mV to 103.21mV. In this case the -16.79mV
overhead is not large enough to cover the -30mV that may be obtained from
the bridge. The bridge must be trimmed externally to bring the offset to within
±30mV. It is not necessary to obtain an exact zero with the external trim.

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

Command: $1RD

Response: *-00022.22

DIN-150 Data Sheet D-5

This value is within the ±30mV offset necessary to provide enough head­room for the strain gage bridge.

Trim out the remaining offset with the Trim Zero (TZ) command:

Command: $1WE
Response: *

Command: $1TZ+00000.00
Response: *

The bridge is now trimmed to zero. Verify:

Command: $1RD

Response: * +00000.00

The Trim Zero (TZ) command may be used at any time to balance out offsets
due to temperature, residual stress, tare, etc.

Excitation

DIN-150 modules may be ordered with either 5V or 10V excitation. Maxi­mum excitation current available is 40mA. Modules with 10V excitation may
be used with bridges that have input impedances of 166 ohms or greater.
Half-bridges of 120 Ω strain gages may be used with 10V excitation if the
bridge is completed with 350 Ω resistors. Modules with 5V excitation will
source bridges of 85 Ω and up.

The actual excitation voltage may vary ±0.5V from the nominal values of
+10V and +5V. However, the module’s internal microprocessor constantly
monitors the actual excitation voltage and provides compensation for any
deviation from the nominal value. This results in a constant data output for
a constant bridge load even if the excitation changes. From a user’s point
of view, the excitation voltage will appear to be exactly +10V or +5V.

Calibration

Since the DIN-150 modules use a ratiometric technique to compensate for
variances in the excitation voltage, special consideration is required to
properly calibrate the unit. Figure D-3 shows the calibration setup. The
Digital Voltmeter (DVM) must be capable of measuring the excitation
voltage to 4 digit accuracy. The voltage source must be able to provide
millivolt signals accurate to ±5 microvolts. The resistive divider may be
constructed from 1% resistors of equal value from 100 to 1000 Ω. The
resistor divider places the voltage source in the center of the common-mode
range of the input amplifier for best accuracy.

DIN-150 Data Sheet D-6

Figure D-3 DIN-150 Calibration

Step 1: power up the unit under test and let it warm up for at least two
minutes.

Step 2: set the voltage source to 0 volts (short). Perform a TZ+00000.00
(Trim Zero) command to eliminate any common-mode offset errors.

Step 3: measure the excitation voltage with the DVM. Divide the result by the
nominal excitation voltage, either 10V or 5V, to obtain a “compensation
factor” = CF.

Step 4: calculate the correct calibration voltage to apply to the unit.

For ±30mV units the voltage is V = +50mV X CF
For ±100mV units the voltage is V = +100mV X CF
Set the voltage source to the calculated voltage V.

Step 5: trim the unit with the Trim Span (TS) command.

For ±30mV modules the command is $1TS+00050.00
For ±100mV modules the command is $1TS+00100.00

Step 6: verify the trim using the $1RD command. The result should be either
*+00050.00 or *+00100.00

Calibration Example:
We wish to calibrate a DIN-151 module. This unit contains 5V excitation and

a ±30mV input.
Step 1 is straightforward and needs no further explanation.
Step 2: set the voltage source to 0 volts. Trim zero:

Command: $1WE
Response: *

DIN-150 Data Sheet D-7

DIN-150 Data Sheet D-8

Command: $1TZ+00000.00
Response: *

Step 3: measure the excitation voltage with the DVM. In this example the
measured voltage is 4.954V Calculate the “compensation factor”:

CF = 4.954 / 5 = 0.9908

Step 4: calculate the calibration voltage:

V = +50mV X 0.9908 = +49.54mV.
Set the voltage standard to +49.54mV.

Step 5: perform the Trim Span command:

Command: $1WE
Response: *

Command: $1TS+00050.00
Response: *

Step 6: verify the calibration, continuing to apply +49.54mV to the input:

Command: $1RD
Response: *+00050.00

The span trim is now complete. The Trim Zero (TZ) command may be used
to trim sensor offsets without affecting the span trim.

Appendix E

DIN-100 Specifications

Specifications (typical @ +25° C and nominal power supply unless
otherwise noted.)

Analog

• Single channel analog input.

• Maximum CMV, input to output at 60Hz: 500V rms.

• Leakage current, input to output at 115Vrms, 60Hz: <2µA rms.

• 15 bit measurement resolution.

• 8 conversions per second.

• Autozero & autocalibration—no adjustment pots.

Digital

• 8-bit CMOS microcomputer.

• Digital scaling, linearization and calibration.

• Nonvolatile memory eliminates pots and switches.

Digital filtering

• Small and large signal with user selectable time
constants from 0 to 16 seconds.

Communications

• Communications in ASCII via RS-232C, RS-485 ports.

• Selectable baud rates: 300, 600, 1200, 2400, 4800, 9600, 19200,

38400.

• NRZ asynchronous data format; 1 start bit, 7 data bits, 1 parity bit and 1
stop bit.

• Parity: odd, even, none.

• User selectable channel address.

• ASCII format command/response protocol.

• Up to 122 multidrop modules per host serial port.

• Communications distance up to 4,000 feet (RS-485).

• Transient suppression on RS-485 communications lines.

• Communications error checking via checksum.

• Can be used with "dumb terminal".

• Scan up to 250 channels per second.

• All communications setups stored in EEPROM.

Power

Requirements: 5V±0.5Vdc, 0.75W max (DIN-150, 2.0W max.).
Internal switching regulator.
Protected against power supply reversals.

Specifications E-2

Environmental

Temperature Range: Operating -25°C to +70°C.

Storage -25°C to +85°C.

Relative Humidity: 0 to 95% noncondensing.

Warranty

12 months on workmanship and material.

DIN-110 Voltage Inputs

• Voltage ranges: ±10mV,±100mV, ±1V, ±5V, ±10V, ±100Vdc.

• Resolution: 0.01% of FS (4 digits).

• Accuracy: ±0.02% of FS max.

• Common mode rejection: 100dB at 50/60Hz.

• Zero drift: ±1 count max (autozero).

• Span tempco: ±50ppm/°C max.

• Input burnout protection to 250Vac .

• Input impedance: ≤ ±1V input = 100MΩ min.

≥ ±5V input = 1MΩ min.

DIN-120 Current Inputs

• Current ranges: 4-20mAdc.

• Resolution: ±0.04% of FS.

• Accuracy: ±0.04% of FS (4-20mA).

• Common mode rejection: 100dB at 50/60Hz.

• Zero drift: ±1 count max (autozero).

• Span tempco: ±50ppm/°C max.

• Voltage drop: ±0.1V max.

DIN-130 Thermocouple Inputs

• Thermocouple types: J, K, T, E, R, S, B, C (factory set).

• Ranges:J = -200°C to +760°C B = 0°C to +1820°C

K = -150°C to +1250°C S = 0°C to +1750°C
T = -200°C to +400°C R = 0°C to +1750°C
E = -100°C to +1000°C C = 0°C to +2315°C

• Resolution: ±1°.

• Overall Accuracy (error from all sources) from 0 to +40°C ambient:

±1.0 °C max (J, K, T, E).
±2.5 °C max (R, S, B, C)(300°C TO FS).

• Common mode rejection: 100dB at 50/60Hz.

• Input impedance: 100MΩ min.

• Lead resistance effect: <20µV per 350Ω.

• Open thermocouple indication.

• Input burnout protection to 250Vac.

• Overrange indication.

• Automatic cold junction compensation and linearization.

Specifications E-3

DIN-140 RTD Inputs

• RTD types: α = .00385, .00392, 100Ω at 0°C,

.00388, 100Ω at 25°C.

• Ranges: .00385 = -200°C to +850°C.

.00392 = -200°C to +600°C.
.00388 = -100°C to +125°C.

• Resolution: 0.1°.

• Accuracy: ±0.3°C.

• Span tempco: ±50 ppm/°C max.

• Common mode rejection: 100dB at 50/60Hz.

• Input connections: 2, 3, or 4 wire.

• Excitation current: 0.25mA.

• Lead resistance effect:3 wire - 2.5°C per Ω of imbalance.

4 wire - negligible.

• Max lead resistance: 50Ω.

• Input burnout protection to 120Vac .

• Automatic linearization and lead compensation.

DIN-145 Thermistor Inputs

• Thermistor types: 2252Ω at 25°C, TD Series

• Ranges:2252Ω = -0°C to +100°C.

TD = -40°C to +150°C.

• Resolution: 2252Ω = 0.01°C or F.

TD = 0.1°C or F

• Accuracy:2252Ω = ±0.1°C.

TD = ±0.2°C

• Common mode rejection: 100dB at 50/60Hz.

• Input protection to 30Vdc .

DIN-150 Bridge Inputs

• Voltage Ranges: ±30mV, ±100mV.

• Resolution: 10µV (mV spans).

0.02% of FS (V span).

• Accuracy: ±0.05% of FS max.

• Common mode rejection: 100dB at 50/60Hz.

• Input burnout protection to 30Vdc .

• Offset Control: Full input range.

• Excitation Voltage: 5V, 10Vdc, 60mA max.

• Zero drift: ±1µV/°C max.

• Span tempco: ±50ppm/°C max.

DIN-160 Timer and Frequency Inputs

• Input impedance: 1M Ω.

• Switching level: selectable 0V, +2.5V.

• Hysteresis: Adjustable 10mV-1.0V.

• Input burnout protection: 250Vac .

Specifications E-4

Frequency Input

• Range: 1Hz to 20KHz.

• Resolution: 0.005% of reading + 0.01Hz.

• Accuracy: ±0.01% of reading ±0.01Hz.

• Tempco: ±20ppm/ °C.

DIN-170 Digital Inputs/Outputs

• 6 digital inputs or 6 output bits.

• Input voltage levels: 0-30V without damage.

• Input switching levels: High, 3.5V min., Low, 1.0V max.

• Outputs: Open collector to 30V, 100mA max. load.

• Vsat: 1.0V max @ 100mA.

• Inputs/Outputs are read/set in parallel.

• Isolated from power supply ground.

DIN-190 RS-232/485 Converter/Repeater

• Baud Rates: 300-115200 (Dip-switch selectable).

• Termination and biasing resistors included (selectable via internal
jumpers).

Appendix F

Modbus Protocol

MODBUS PROTOCOL OVERVIEW

This document describes the Modbus RTU protocol option included in the
DIN-100 series of data acquisition modules. This implementation of the
Modbus protocol is a subset of the protocol as described in the Modicon
Modbus Protocol Reference Guide PI-MBUS-300 Rev F. Only the RTU
version of the protocol has been implemented.

Modbus RTU mode communicates in standard NRZ asynchronous format
with one start bit, eight data bits, one parity bit, and one stop bit. Even and
odd parity is supported. If no parity is specified, the number of stop bits can
be user configured for either one or two stop bits.

Baud rates supported at this time are: 300, 600, 1200, 2400, 4800, 9600,
19,200 and 38,400.

Modbus uses the RS-485 electrical specification for multidrop communica­tions. The RS-232 electrical specification is not supported.

Modbus is a registered trademark of AEG Modicon Inc.
The Modbus RTU protocol transmits data in 8-bit binary bytes (not ASCII).

To illustrate the data in this document, the 8-bit byte is described as two
hexadecimal nibbles. For example, the binary byte value “0101 1101” will be
written as 5D.

A typical Modbus RTU command may look like this:

01 04 00 00 00 01 31 CA

Remember, this command string and others throughout this docu­ment are actually transmitted to a module as eight 8-bit binary charac­ters.

The actual format of the data is dependent on the type of command desired.
The example above is the Modbus ‘Read Input Registers’ function.

The ‘01’ is the address of the slave device (DIN-100 module) being
commanded. Each slave device must have its own unique address.

The ‘04’ specifies the Modbus ‘Read Input Registers’ function. This is
equivalent to the ‘Read Data’ command to obtain analog input data.

Modbus Protocol F-2

The next two characters ‘00 00’ specify the starting address of the registers
to be read. The first Modicon input register 30001 is addressed as ‘00 00’.
Register 30005 is addressed as ‘00 04’, etc.

The next two characters of this command specify the number of registers to
be read, including the starting register. In this case the two binary characters
‘00 01’ indicates only one register is to be read.

The final two characters of the command string make up the Cyclical
Redundancy Check (CRC), used to check for errors in the message.

There are no prompt or terminating characters in the messages. All
messages must be transmitted as continuous strings. Messages are termi­nated by a ‘silent’ interval of at least 3.5 character times. A ‘silent’ interval
of more than 1.5 character times marks the beginning of the next message.
Therefore it is mandatory that the RS-485 bus must be biased in the MARK
condition during the ‘silent’ interval. This is usually accomplished by pull-up
and pull-down resistors on the communications line.

A typical response to this example command could be:

01 04 02 80 00 D8 F0

The ‘01’ and ‘04’ characters echo the slave address and the command
function.

For this particular command function, the ‘02’ character indicates the
number of data characters to follow, in this case, 2 characters.

The two character string ‘80 00’ is the value read from Modicon input register

30001. Register data is read back as 16 bits.
The remaining two characters, ‘D8 F0’ is the CRC for the response.
The A1000 and DIN-190 series of RS-232 to RS-485 protocol converters

and repeaters will not operate with the 9-bit data characters used by the
Modbus protocol.

Getting Started

Modbus Protocol F-3

The DIN-100 series modules are initialized at the factory to communicate
using the DIN-100 ASCII protocol. This allows for all setup and configura­tions to be easily performed using the DIN-100 setup software or a dumb
terminal. After the setup process has been completed the DIN-100 can be
placed in Modbus RTU protocol mode using the “MBR” command. Disable
the Modbus RTU mode using the Modbus Disable (“MBD”) command.

Quick start steps:
1 Connect a power supply to the DIN-100 between +Vs terminal and GND

terminal. The regulated supply voltage must be +5.0Vdc.

2. Properly connect the DIN-100 series to a computer using the “quick hook­up” diagrams in chapter #1 of this manual using either an RS-232 or RS-485
serial port.

3. Locate the Windows Utility software CD-ROM and run the setup.exe file
to install the software. An Omega Data Acquisition menu selection will be added
to the Windows “Start, Programs” menu. The Utility Software will be listed
under that selection.

4. Configure the host computer serial ports by selecting main menu selection
“Edit” and “Serial Ports”. Select the correct COMx: port, baud rate and Parity
type. Note: If the “Default*” pin on DIN-100 is connected to GND then select
300 baud as host computer baud rate and select no parity.

5. Select main menu “Setup” and enter the DIN-100 device address and
model number. For example, select “111 DIN +/-100mV/RS-485 Out”.

6. At the next configuration screen make the necessary alterations to Baud
Rate, Parity type and other required parameters. Drop down the “Commu­nications Protocol” list box and select “Modbus RTU Protocol”. Specifiy the
correct Modbus slave address and press the <APPLY> to transmit the new
setup values. Once the values have been transmitted press the <ESC> key
back to the program main menu.

7. Remove the connection between “Default*” and GND, which performs
internal reset, to enable Modbus RTU mode. If there was no connection
between “Default*” and GND then cycle the power on device to force a reset
and enable Modbus Mode.

The device is now configured for Modbus RTU mode and can be connected

Modbus Protocol F-4

to a RS-485 based Modbus master system.

MODBUS Function Codes

Modbus protocol compatible devices communicate using a master-slave
technique similar to that used in ASCII protocol. In a master-slave commu­nications system only one device (the master) can initiate a communications
sequence. All others devices (the slaves) respond when requested by the
master. Typical master devices can be personal computers or PLCs. Typical
slave devices are DIN-100 modules.

The master can address any slave device. Slave devices return a message
to any command that was addressed specifically to them. The returned
messages are considered response messages.

The Modbus protocol format used by a master consists of a device address,
a command function code which defines the operation to be performed, data
required with the command, and an error checking value. The slave
response message contains any required data and an error checking value.
If an error occurs, an exception code will be generated.

The supported master function codes are discussed below.
01 - Read Coil Status (Digital Inputs)

04 - Read Input Register (Analog Inputs)
05 - Force Single Coil (Digital Output)
06 - Preset Single Register (Return to ASCII protocol)
15 - Force Multiple Coils (Digital Outputs)

Function (01) Read Coil Status (Digital Inputs)

Modbus function (01) Read Coil Status will read the status of both the digital
inputs and digital outputs. Digital outputs are read as the state of the data
on the microprocessor output port before being buffered by the open­collector transistor. If the coil status of a digital output returns as ‘1’, this
means that this particular bit (coil) is turned “on” or sinking current on the
corresponding module digital output pin. Depending on the module type,
some of the digital outputs may not be implemented.

Modbus relay input coils are considered digital inputs on the DIN-100 series
modules. Modbus relay output coils are considered digital outputs on the
DIN-100 series modules. This function can be used to read status of the
digital inputs or the combined status of both the digital inputs and digital
outputs.

Modbus Protocol F-5

DIN-100 digital output bits B00 to B05 correspond to Modbus coils 00 00 to
00 05.

DIN-100 digital input bits B00 to B05 correspond to Modbus coils 00 08 to
00 0D.

The DIN-100 series digital inputs and outputs are register mapped as two
8-bit bytes (16-bits), one byte for inputs and one byte for outputs. The least­significant byte represent the status of up to 8 digital outputs. The most­significant byte represents the status of up to 8 digital input bits. The register
contents can be interrogated as 8-bits of digital input data or together as 16­bits of digital inputs and outputs data.

Exception errors will be generated by the module if attempting to read or
write to more than 16 bits.

The following example can be used to read only the digital input status:

Command: 01 01 00 08 00 08 BC 0E
Response: 01 01 01 FF 11 C8

In the command string:
01 is the slave address
01 is the Read Coil Status command
00 08 is the starting coil number
00 08 is the number of bits to read
BC 0E is the CRC to this message

In the response string:
01 is the slave address
01 is the Read Coil Status command
01 is the number of data bytes returned
FF is the Digital Inputs status data
11 C8 is the CRC for this message

The following example can be used to read the status of both the digital
inputs and outputs:

Command: 01 01 00 00 00 10 3D C6
Response: 01 01 02 09 FF FF EC

In the command string:

Modbus Protocol F-6

01 is the slave address
01 is the Read Coil Status command
00 00 is the starting coil address
00 10 is the number digital bits to read
3D C6 is the CRC to this message

In the response string:
01 is the slave address
01 is the Read Coil Status command
02 is the number of data bytes returned
09 is the Digital Output status
FF is the Digital Inputs status
FF EC is the CRC for this message

Function (04) - Read Input Register (Analog Inputs)

Read Input Register function (04) is the primary command to acquire analog
input data. This command function supports reading of up to 16 input
registers starting from Modbus slave register 30001. The registers are
addressed starting from zero meaning registers 1-16 are addressed as 0-

15.
The response data for each channel is returned as two bytes that represent

a 16-bit binary value. The 16-bit value is scaled as a percentage of the full
scale input range. The first byte contains the high order bits and the second
contains the low order bits. The binary analog values for each channel can
range from 0000-FFFF (hexadecimal).

Only the register values for channel one are valid as each module contains
a single analog input. The remaining data values for channels 2-16 will
always return as 0000 (hexadecimal).

A typical command and response to read the analog input value from
Modbus device address 01 is:

Command: 01 04 00 00 00 01 31 CA
Response: 01 04 02 14 57 F7 CE

In the command string:
01 is the slave address
04 is the Read Input Registers command
00 00 is the starting register to be read (Modbus address 30001)
00 01 specifies the number of registers to be read, in this case, one register.

Modbus Protocol F-7

31 CA is the CRC for this message
In the response string:

01 is the slave address
04 is the command
02 indicated the number of data bytes in the message, in this case, two
bytes
14 57 is the analog data
F7 CE is the CRC for this message

This sample command reads two registers:

Command: 01 04 00 00 00 02 71 CB
Response: 01 04 04 14 58 00 00 7F A7

The analog data from Modbus register 30001 is 14 58.
The data from Modbus register 30002 is set to 00 00.

The analog data is scaled so that 00 01 represents the Negative Full Scale
value programmed into the module. FF FE represents the Positive Full Scale
value programmed into the module.

For example, for a ±10 volt input module:
00 01 corresponds to -10 volts
80 00 corresponds to 0 volts
FF FE corresponds to +10 volts

A negative overload where the analog input exceeds minus full scale value
is represented by 00 00 (hexadecimal).

A positive overload where the analog input exceeds the positive full scale
value is represented by FF FF (hexadecimal).

Function (05) - Force Single Coil (Digital Output)

The Force Single Coil function (05) is used to set or clear a single Modbus
output relay coil. Each output relay coil is considered a digital output on the
DIN-100 series modules. Modbus Coil #1 equals DIN-100 series digital
output bit B00 and Coil #6 equals digital output bit B05.

The following example can be used to turn on digital output bit B00:

Modbus Protocol F-8

Command: 01 05 00 00 FF 00 8C 3A
Response: 01 05 00 00 FF 00 8C 3A

In the command string:
01 is the slave address
05 is the Force Single Coil command
00 00 is the address of the digital output bit, 00 07 would equal B07
FF 00 indicates that the desired bit will be set or turned on
8C 3A is the CRC for this message

The valid address range of digital output bits is 00 00 to 00 07. Any other
address will produce an exception (error) response.

To clear or turn off digital output bit B03, replace the FF 00 string with 00 00.
For example:

Command: 01 05 00 03 00 00 3D CA
Response: 01 05 00 03 00 00 3D CA

Command values other than FF 00 or 00 00 will result in an exception (error)
response.

Function (06) - Preset Single Register (Return to DIN-100 ASCII Proto­col)

The Preset Single Register function (06) can be used to temporarily suspend
the Modbus RTU protocol and force the module into DIN-100 ASCII
protocol. Write a value of 0000 to Modbus register 40001 to temporarily
suspend Modbus RTU mode. The module will then communicate using the
DIN-100 ASCII protocol only.

The DIN-100 ASCII protocol can be used to alter or check setup information
and/or for troubleshooting purposes. The module will continue to communi­cate using the ASCII protocol until either a Remote Reset (RR) command
(RR) is received or the power is cycled. At which time, the module will return
to the Modbus RTU protocol mode.

Refer to the DIN-100 ASCII Modbus Disable command (MBD) for more
information on disabling the Modbus protocol.

Command: 01 06 00 00 00 00 89 CA
Response: 01 06 00 00 00 00 89 CA
Function (15) - Force Multiple Coils (Digital Outputs)

Modbus Protocol F-9

The Force Multiple Coils function (15) is used to force multiple Modbus
output relay coils to a desired ON or OFF state. This function is similar in
operation to the DIN-100 ASCII digital output command (DO) in that it
updates the status of all available output coils at once. The state of each
output coil is set ON or OFF according to the digital data value received with
the function.

The digital output bits are referred to as “output relay coils” in the Modbus
protocol. The DIN-100 series digital output bit B00 equals Modbus output
relay Coil#1 and digital output bit B05 equals output relay Coil#6. DIN-100
series modules with less than eight digital outputs also equate output bit B00
with output relay Coil#1 and count up by one for each additional output bit.

The following example can be used to turn on two digital output bits on a DIN­113 module.

Command: 01 0F 00 00 00 02 00 03 9F 06
Response: 01 0F 00 00 00 02 D4 0A

In the command string:
01 is the slave address
05 is the Force Single Coil command
00 00 is the starting address of the digital output bits to be changed, 00 07
would equal B07
00 02 specifies the number of output relay coils to be changed
00 03 specifies the digital output data value in HI byte LO byte format.
Note: The HI byte will always be zero as DIN-100 series modules contain up
to eight digital outputs
9F 06 is the CRC for this message

The valid address range of digital output bits is 00 00 to 00 07. Any other
address will produce an exception (error) response.

To clear or turn off the digital output bits, replace the 00 03 string with 00 00.
For example:

Command: 01 0F 00 00 00 02 00 00 DF 07
Response: 01 0F 00 00 00 02 D4 0A

Modbus RTU Enable (MBR)

Modbus Protocol F-10

To place any DIN-100 module in Modbus protocol mode use the Modbus
RTU (MBR) command. The MBR command must be used to specify the
Modbus device address and enable the Modbus protocol mode. The device
address consists of a two character hexadecimal value and is stored in
EEPROM. The two byte address specified is translated to a one byte, 8 bit
address required by the Modbus protocol. The example below can be used
to specify a Modbus device address of “01”.

Command: $1MBR01
Response: *

Command: #1MBR01
Response: *1MBR019D

After the Modbus address is specified, a reset is necessary to activate the
Modbus protocol mode. The reset may be accomplished in one of three
ways:

1) Removing power for about 10 seconds to perform a power-up reset.

2) Momentarily grounding the Default* pin.

3) Issue a Write Enable (WE) command followed by a Remote Reset
(RR) command.

After a reset is performed, the module is in Modbus protocol mode.

Modbus Disable (MBD)

The Modbus Disable (MBD) command is used to disable the Modbus
protocol. Any DIN-100 series module in Modbus mode can be returned to
DIN-100 ASCII protocol mode by connecting a jumper wire between module
pins GND and Default* pin. This places the module in Default Mode, where
the module will only communicate at 300 baud, no parity, DIN-100 ASCII
protocol, and answer to any address. While in Default mode, transmit an
MBD command to internally disable the Modbus protocol.

Following the MBD command a device reset must occur. The reset is
necessary to activate the DIN-100 ASCII protocol. A reset can occur by
removing the Default* jumper, performing a power-up reset or by transmit­ting a Write Enable (WE) and Remote Reset (RR) command sequence.

After a reset is performed, the module is in DIN-100 ASCII protocol mode.

Modbus Protocol F-11

Command: $1MBD
Response: *

Command: #1MBD
Response: *1MBD2E

Modbus Exception Responses

The following standard Modbus exception codes (error messages) are
supported:

01 Illegal Function

This exception code is generated when the function code is not

recognized by the module.

02 Illegal Data Address

This code is generated when the specified data address in the

command is not supported by the module.

03 Illegal Data Value

This exception code is returned if the command data is out of

range for the function.

06 Slave Device Busy

After the module is reset by power-up, a ‘RR’ command, or return
from Default Mode, the module performs an initial self-calibrationfor a pe­riod of about 3 seconds. During this time any command sent to the mod­ule will result in a ‘busy’ exception response.

Where Do I Find Everything I Need for

Process Measurement and Control?

OMEGA…Of Course!

Shop online at omega.com

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Rotameters, Gas Mass Flowmeters & Flow Computers

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Turbine/Paddlewheel Systems

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pH/CONDUCTIVITY

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pH Electrodes, Testers & Accessories

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Benchtop/Laboratory Meters

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Controllers, Calibrators, Simulators & Pumps

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DATA ACQUISITION

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ENVIRONMENTAL
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M3647/0605

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and
workmanship for a period of 13 months from date of purchase. OMEGA’s WARRANTY adds an
additional one (1) month grace period to the normal one (1) year product warranty to cover
handling and shipping time. This ensures that OMEGA’s customers receive maximum
coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer
Service Department will issue an Authorized Return (AR) number immediately upon phone or
written request. Upon examination by OMEGA, if the unit is found to be defective, it will be
repaired or replaced at no charge. OMEGA’s WARRANTY does not apply to defects resulting
from any action of the purchaser, including but not limited to mishandling, improper interfacing,
operation outside of design limits, improper repair, or unauthorized modification. This
WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence
of having been damaged as a result of excessive corrosion; or current, heat, moisture or vibra­tion; improper specification; misapplication; misuse or other operating conditions outside of
OMEGA’s control. Components in which wear is not warranted, include but are not limited to
contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability
for any damages that result from the use of its products in accordance with information
provided by OMEGA, either verbal or written. OMEGA warrants only that the parts
manufactured by the company will be as specified and free of defects. OMEGA MAKES
NO OTHER WARRANTIES OR REPRESENTATIONS OF ANY KIND WHATSOEVER,
EXPRESSED OR IMPLIED, EXCEPT THAT OF TITLE, AND ALL IMPLIED WARRANTIES
INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF LIABILITY: The remedies of pur­chaser set forth herein are exclusive, and the total liability of OMEGA with respect to this
order, whether based on contract, warranty, negligence, indemnification, strict liability or
otherwise, shall not exceed the purchase price of the component upon which liability is
based. In no event shall OMEGA be liable for consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as
a “Basic Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity;
or (2) in medical applications or used on humans. Should any Product(s) be used in or with any
nuclear installation or activity, medical application, used on humans, or misused in any way,
OMEGA assumes no responsibility as set forth in our basic WARRANTY/ DISCLAIMER language,
and, additionally, purchaser will indemnify OMEGA and hold OMEGA harmless from any liability
or damage whatsoever arising out of the use of the Product(s) in such a manner.

RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department.
BEFORE RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN
AUTHORIZED RETURN (AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT
(IN ORDER TO AVOID PROCESSING DELAYS). The assigned AR number should then be
marked on the outside of the return package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to
prevent breakage in transit.

FOR WARRANTY

RETURNS, please have
the following information available BEFORE
contacting OMEGA:

1. Purchase Order number under which

the product was PURCHASED,

2. Model and serial number of the product

under warranty, and

3. Repair instructions and/or specific

problems relative to the product.

FOR NON-WARRANTY REPAIRS,

consult
OMEGA for current repair charges. Have the
following information available BEFORE
contacting OMEGA:

1. Purchase Order number to cover the

COST of the repair,

2. Model and serial number of the

product, and

3. Repair instructions and/or specific problems

relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible.
This affords our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2005 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without
the prior written consent of OMEGA ENGINEERING, INC.

Where Do I Find Everything I Need for

Process Measurement and Control?

OMEGA…Of Course!

Shop online at omega.com

TEMPERATURE

䡺⻬

Thermocouple, RTD & Thermistor Probes, Connectors, Panels & Assemblies

䡺⻬

Wire: Thermocouple, RTD & Thermistor

䡺⻬

Calibrators & Ice Point References

䡺⻬

Recorders, Controllers & Process Monitors

䡺⻬

Infrared Pyrometers

PRESSURE, STRAIN AND FORCE

䡺⻬

Transducers & Strain Gages

䡺⻬

Load Cells & Pressure Gages

䡺⻬

Displacement Transducers

䡺⻬

Instrumentation & Accessories

FLOW/LEVEL

䡺⻬

Rotameters, Gas Mass Flowmeters & Flow Computers

䡺⻬

Air Velocity Indicators

䡺⻬

Turbine/Paddlewheel Systems

䡺⻬

Totalizers & Batch Controllers

pH/CONDUCTIVITY

䡺⻬

pH Electrodes, Testers & Accessories

䡺⻬

Benchtop/Laboratory Meters

䡺⻬

Controllers, Calibrators, Simulators & Pumps

䡺⻬

Industrial pH & Conductivity Equipment

DATA ACQUISITION

䡺⻬

Data Acquisition & Engineering Software

䡺⻬

Communications-Based Acquisition Systems

䡺⻬

Plug-in Cards for Apple, IBM & Compatibles

䡺⻬

Datalogging Systems

䡺⻬

Recorders, Printers & Plotters

HEATERS

䡺⻬

Heating Cable

䡺⻬

Cartridge & Strip Heaters

䡺⻬

Immersion & Band Heaters

䡺⻬

Flexible Heaters

䡺⻬

Laboratory Heaters

ENVIRONMENTAL
MONITORING AND CONTROL

䡺⻬

Metering & Control Instrumentation

䡺⻬

Refractometers

䡺⻬

Pumps & Tubing

䡺⻬

Air, Soil & Water Monitors

䡺⻬

Industrial Water & Wastewater Treatment

䡺⻬

pH, Conductivity & Dissolved Oxygen Instruments

M3647/0605