Omega Products D1711 Installation Manual

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User’s Guide

D1700 Series

Digital Transmitters

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1700 USERS MANUAL

REVISED: 5/1/94

Omega Engineering
One Omega Drive
P O Box 4047
Stamford, CT 06907
Phone: 1-800-DAS-IEEE
Fax: [phone]
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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.

The 1700 series are not intrinsically safe devices and should not be
used in an explosive environment unless enclosed in approved
explosion-proof housings

TABLE OF CONTENTS

CHAPTER 1 Getting Started

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

CHAPTER 2 Functional Description

Block Diagram 2-1

CHAPTER 3 Communications

Data Format 3-2
RS-232 3-2
Multi-party Connection 3-3
Software Considerations 3-4
Changing Baud Rate 3-5
RS-485 3-6
RS-485 Multidrop System 3-7

CHAPTER 4 Command Set

Table of Commands 4-7
User Commands 4-8
Error Messages 4-26

CHAPTER 5 Setup Information and Command

Command Syntax 5-1
Setup Hints 5-10

CHAPTER 6 Continuous Input/Output

Applications 6-2

CHAPTER 7 Power Supply

CHAPTER 8 Troubleshooting

Appendix A ASCII Table

Appendix B H1770 64 Channel I/O Board

Appendix C H1750 24 Channel Digital I/O

Appendix D 1700 Series Specifications

Chapter 1

Getting Started

Introduction

The 1700 Series of Digital I/O to Computer Interfaces provide computer
monitoring and control of devices through solid state relays or TTL signals.
The status of inputs and outputs is communicated to the host in ASCII format
using RS-232C or RS-485 serial communications.

With the 1700 series the user can control digital inputs and outputs individu­ally or all at once. Any channel may be designated as an input or output by
the user. Many industrial applications require a safe start-up condition to
prevent accidents at critical points in the process.The onboard nonvolatile
EEPROM memory stores the user-specified initial condition (input or output)
of each channel; thereby eliminating the need for software initialization
routines when power is applied or restored.

The 1700 series may be setup in special modes which allow them to
communicate without being polled by a host computer. Collectively these
modes are called Continuous Input/Output Modes. In many applications the
burden on the host may be greatly simplified and in some cases the host may
be eliminated altogether.

The 1700 series include:
1711/1712 15 channel I/O modules.
H1750 24 channel I/O board.
H1770 64 channel I/O board.

Getting Started

The instructions in this chapter cover all 1700 models; however, for simplicity
we use the 1711 & 1712 in the figures. If you have an H1700 board see the
appropriate appendix for instructions on getting started.

Default Mode

All models contain an EEPROM (Electrically Erasable Programmable Read
Only Memory) to store setup information. The EEPROM replaces the usual
array of switches 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 settings. There

Getting Started 1-2

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

RS-232 & RS-485 Quick Hook-Up

Software is not required to begin using your 1700 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 $1DI and pressing the Enter or Return key. The module will

Getting Started 1-3

respond with an * followed by the data reading at the input, typically 8000.
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, no echo and two­character delay. Refer to the Chapter 5 to configure the module to your
application.

Figure 1.1 RS-232 Quick Hook-Up.

Figure 1.2 RS-485 Quick Hook-Up.

Getting Started 1-4

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 1.3 shows the hook-up.
This connection will work provided the RS-232C transmit
output is current limited to less than 50mA and the RS­232C 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.

Getting Started 1-5

Figure 1.3 RS-485 Quick Hook-Up with an RS-232 Port.

S1000 Software

Software is available to assist the user in setting up the 1700 modules.
The S1000 software runs on the IBM compatible PC’s and is available
free of charge.

Chapter 2

Functional Description

The D1700 Digital I/O modules provide remote control and monitoring of on­off signals in response to simple commands from a host computer. Digital
commands are transmitted to the D1700 units using standard RS-232 or RS­485 communications links. Commands and responses are in the form of
simple English ASCII character strings for ease of use. The ASCII protocol
allows the units to be interfaced with dumb terminals and modems as well as
intelligent controllers and computers.

Figure 2.1 Digital I/O Functional Block Diagram.
Figure 2.1 shows a functional block diagram of a D1712. An 8-bit CMOS

microprocessor is used to provide an intelligent interface between the host
and the bi-directional I/O lines. The microprocessor receives commands and
data from the host computer through a serial communications port. Special­ized communications components are used to interface the microprocessor
to the RS-485 communications standard. Commands received by the
microprocessor are thoroughly checked for syntax and data errors. Valid
commands are then processed to complete the desired function. A wide
variety of commands are available to configure and control the digital I/O

Functional Description 2-2

lines. Responses to the host commands are then produced by the micro­processor and transmitted back to the host over the RS-485 serial link.

An Electrically Erasable Programmable Read-Only Memory (EEPROM) is
used to retain important data even if the module is powered down. The
EEPROM contains setup information such as the address, baud rate, and
parity as well as I/O configuration data.

Each digital line on the D1712 is bidirectional and may be individually
configured by the user to be an input or an output. The direction assign­ments of all the lines are stored in EEPROM so that the lines are
automatically configured each time the D1712 is powered up.

Figure 2.2 Digital I/O Circuit.
Figure 2.2 is a detail diagram of a single I/O line circuit. The output driver

is a darlington circuit capable of sinking 100mA with a maximum output
voltage of 30V. The maximum total current that may be handled by the
D1711 or D1712 package is 1A. The output saturation voltage at 100mA
is 1.2V max. Pullup resistors are not provided in the modules.

When the I/O pin is configured as an input, the output driver is turned off.
The input state is read by the microprocessor through an input protection
circuit consisting of a 100K resistor and diodes. This allows the input values

Functional Description 2-3

to range from 0 to 30V without damaging the microprocessor. Note that with
the output driver off, the 100K resistor produces a leakage current if the I/
O line is greater than +5V.

When a read function is performed on an I/O pin, the actual logical state of
the pin is read back even if the pin is configured as an output. this provides
a means to verify the state of the output.

Figure

2.3 Digital Outputs Used With Relays.
Figure 2.3 shows typical connections to solid-state relays and electrome-

chanical relays. When electromechanical relays are used, always include
a flyback diode to avoid damage to the output driver.

Functional Description 2-4

Figure 2.4 D1711, D1712 Events Counter Circuit.
Figure 2.4 is a detail schematic of the B00/EV pin. This pin is identical to all

other pins but it has the event counter circuitry added on. The event counter
circuitry consists of input protection components and a capacitor to provide
some noise filtering. The event data is buffered by a Schmitt-trigger gate
which outputs the event signal to the microprocessor.

The microprocessor contains a user-programmable filter to debounce the
event counter input. The filter is necessary when the event signal is derived
from mechanical contacts such as switches or relays. The filter constant is
user-selectable for 0,5,20 or 50ms. Figure 2.5 shows the filter action for the
5ms setting.

Figure 2.5 Event Counter Debounce Filter.
The microprocessor samples the event input at 1ms intervals. The input

signal must be high for at least five consecutive samples before it will be

Functional Description 2-5

counted as a high transition. Similarly, the input must be low for five sample
periods before it is counted as a low signal. If the filter is set for 20ms, the
input must be stable for 20 consecutive samples, etc.

The last major block in the diagram is the power supply. The power supply
converts the raw 10 to 30 volts supplied by the user into regulated voltages
used in the module. It produces +5V necessary to operate the microproces­sor and EEPROM. On RS-232 units, the power supply produces ±10V

necessary for the RS-232 communications standard.

Chapter 3

Communications

Introduction

The D1700 modules have 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. For computers that support RS-232C, no special
machine language software drivers are necessary for operation. The mod­ules can be connected to auto-answer modems for long-distance operation
without the need for a supervisory computer. 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; 124 with repeaters. A practical limit for RS-232C units
is about ten, although a string of 124 units is possible. 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.

Communication to the D1700 modules is performed with two- or three­character ASCII command codes such as DO for Digital Output. A complete
description of all commands is given in the Chapter 4. A typical command/
response sequence would look like this:

Command: $1RD
Response: *+99999.99

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

Communications 3-2

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:

Mnemonic Timeout
ACK, CB, CE, CP, DI, DO, RA, RAB, RAP, RB, ≤ 5.0 ms
RD,RP, RS, RSU, SB, SP, RIA, RCM, RR, WE

EC, RE, RWT, RID, RIV, RCT, AIB, AIP, AOB, ≤ 15.0 ms
AOP, CIA, CMC, CMD, CME, CMT

WT, CT, SU, AIO, ID, IV ≤
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.

RS-232C

RS-232C is the most widely used communications standard for information
transfer between computing equipment. RS-232C versions of the 1700
series will interface to virtually all popular computers without any additional
hardware. Although the RS-232C standard is designed to connect a single
piece of equipment to a computer, this system allows for several modules
to be connected in a daisy-chain network structure.The advantages offered
by the RS-232C standard are:

1) widely used by all computing equipment

2) no additional interface hardware in most cases

3) separate transmit and receive lines ease debugging

4) compatible with dumb terminals

Communications 3-3

However, RS-232C suffers from several disadvantages:

1) low noise immunity

2) short usable distance - 50 to 200 feet

3) maximum baud rate - 19200

4) greater communications delay in multiple-module systems

5) less reliable–loss of one module breaks chain

6) wiring is slightly more complex than RS-485

7) host software must handle echo characters

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). The use of echo is not necessary when using a single
module on the communications line.

Multi-party Connection

RS-232C is not designed to be used in a multi-party system; however the
D1700 modules can be daisy-chained to allow many modules to be con­nected to a single communications port. The wiring necessary to create the
daisy-chain is shown in Figure 3.1. Notice that starting with the host, each
Transmit output is wired to the Receive input of the next module in the daisy
chain. This wiring sequence must be followed until the output of the last
module in the chain is wired to the Receive input of the host. All modules in
the chain must be setup to the same baud rate and must echo all received
data (see Setups). Each module must be setup with its own unique address
to avoid communications collisions (see Setups). In this network, any
characters transmitted by the host are received by each module in the chain
and passed on to the next station until the information is echoed back to the
Receive input of the host. In this manner all the commands given by the host
are examined by every module. If a module in the chain is correctly
addressed and receives a valid command, it will respond by transmitting the
response on the daisy chain network. The response data will be ripple
through any other modules in the chain until it reaches its final destination,
the Receive input of the host.

Communications 3-4

Fig-

ure 3.1 RS-232 Daisy Chain.
The daisy chain network must be carefully implemented to avoid the pitfalls

inherent in its structure. The daisy-chain is a series-connected structure
and any break in the communications link will bring down the whole system.
Several rules must be observed to create a working chain:

1. All wiring connections must be secure; any break in the wiring,

power, ground or communications will break the chain.

2. All modules must be plugged into their connectors.

3. All modules must be setup for the same baud rate.

4. All modules must be setup for echo.

Software Considerations

If the host device is a computer, it must be able to handle the echoed
command messages on its Receive input along with the responses from
the module. This can be handled by software string functions by observing
that a module response always begins with a ‘ * ‘ or ‘ ? ‘ character and ends
with a carriage return.

A properly addressed D1700 module in a daisy chain will echo all of the
characters in the command including the terminating carriage return. Upon
receiving the carriage return, the module will immediately calculate and
transmit the response to the command. During this time, the module will not
echo any characters that appear on its receive input. However, if a
character is received during this computation period, it will be stored in the

Communications 3-5

module’s internal receive buffer. This character will be echoed after the
response string is transmitted by the module. This situation will occur if the
host computer appends a linefeed character on the command carriage
return. In this case the linefeed character will be echoed after the response
string has been transmitted.

The daisy chain also affects the command timeout specifications. When a
module in the chain receives a character it is echoed by re-transmitting the
character through the module’s internal UART. This method is used to
provide more reliable communications since the UART eliminates any
slewing errors caused by the transmission lines. However, this method
creates a delay in propagating the character through the chain. The delay is
equal to the time necessary to retransmit one character using the baud rate
setup in the module:

Baud Rate Delay
300 33.30ms
600 16.70ms
1200 8.33ms
2400 4.17ms
4800 2.08ms
9600 1.04ms
19200 520µs
38400 260µs

One delay time is accumulated for each module in the chain. For example,
if four modules are used in a chain operating at 1200 baud, the accumulated
delay time is 4 X 8.33 ms = 33.3 ms This time must be added to the times
listed in Table 3.1 to calculate the correct communications time-out error.

For modules with RS-232C outputs, the programmed communications delay
specified in the setup data (see Chapter 5) is implemented by sending a
NULL character (00) followed by an idle line condition for one character time.
This results in a delay of two character periods. For longer delay times
specified in the setup data, this sequence is repeated. Programmed commu­nications delay is seldom necessary in an RS-232C daisy chain since each
module in the chain adds one character of communications delay.

Changing Baud Rate

It is possible to change the baud rate of an RS-232C daisy chain on-line. This
process must be done carefully to avoid breaking the communications link.

1. Use the SetUp (SU) command to change the baud rate setup on each

Communications 3-6

module in the chain. Be careful not to generate a reset during this process.
A reset can be caused by the Remote Reset (RR) command or power
interruptions.

2. Verify that all the modules in the chain contain the new baud rate
setup using the Read Setup (RS) command. Every module in the chain
must be setup for the same baud rate.

3. Remove power from all the modules for at least 10 seconds. Restore
power to the modules. This generates a power-up reset in each module and
loads in the new baud rate.

4. Change the host baud rate to the new value and check communica­tions.

5. Be sure to compensate for a different communications delay as a
result of the new baud rate.

Using A Daisy-Chain With A Dumb Terminal

A dumb terminal can be used to communicate to a daisy-chained system.
The terminal is connected in the same manner as a computer used as a
host. Any commands typed into the dumb terminal will be echoed by the
daisy chain. To avoid double characters when typing commands, set the
terminal to full duplex mode or turn off the local echo. The daisy chain will
provide the input command echo.

RS-485

RS-485 is a recently developed communications standard to satisfy the
need for multidropped systems that can communicate at high data rates
over long distances. RS-485 is similar to RS-422 in that it uses a balanced
differential pair of wires switching from 0 to 5V to communicate data. RS­485 receivers can handle common mode voltages from -7V to +12V without
loss of data, making them ideal for transmission over great distances. RS­485 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 RS-232C:

1) balanced line gives excellent noise immunity

2) can communicate with modules at 38400 baud

3) communications distances up to 4,000 feet.

4) true multidrop; modules are connected in parallel

5) individual modules may be disconnected without affecting
other modules

6) up to 32 modules on one line; 124 with repeaters

7) no communications delay due to multiple modules

8) simplified wiring using standard telephone cable

Communications 3-7

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 and other RS-485 equipment will become avail­able as the standard gains popularity. An RS-485 system usually requires
an interface.

We offer interface converters to convert RS-232C to RS-485. These
converters also include power supplies to power up to 32 modules. To
expand an RS-485 system even further, repeater boxes are available from
us to string up to 124 modules on one communications port.

RS-485 Multidrop System

Figure 3.2 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. For wire runs greater
than 500 feet total, each end of the line should be terminated with a 220Ω
resistor connected between DATA and DATA*.

When using a bi-directional RS-485 system, there are unavoidable periods

of time when all stations on the line are in receive mode. During this time,
the communications lines are left floating and are very susceptible to noise.
To prevent the generation of random characters, the lines should be biased
in a MARK condition as shown in Figure 3.2. The 1K resistors are used to
keep the DATA line more positive than the DATA* line when none of the RS­485 transmitters are on. When enabled, the low impedance of an RS-485
driver easily overcomes the load presented by the resistors.

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 ‘#’
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 3-8

Communications Delay

All modules with RS-485 outputs 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 3-9

Chapter 4

1700 Command Set

The D1700 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 (unless it is
setup for Continuous Output Mode (see Chapter 6). 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 (the long response format will be covered a little later).

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.
For ease in debugging, 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 or three character command
which 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 full later in this section. 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’ section below.

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’.)

Command Set 4-2

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.

The majority of data values used with the D1700 series is in the form of
hexadecimal (base 16) numbers representing digital data. Each hexadeci­mal ASCII digit represents four bits of digital data. For example: E5 (hex)
= 1110 0101 (binary)

An example command may look like this:

Command: $1DOFFFF

This is an example of the Digital Output (DO) command. This particular
command would be used to turn on 16 bits of data represented by ‘FFFF’.

Data read back from the Event Counter with the Read Events (RE)
command is in the form of a seven-digit decimal number. For example:

Command: $1RE
Response: *0000123

Analog data is represented in a form of sign, five digits, decimal point and
two additional digits:

Command: $1RWT
Response: *+00010.00

The analog data format is used with the WT and CT commands.

Bit Addresses

There are several commands that are used to manipulate a single bit.
These commands require a bit address so that the desired action will be
directed to the correct I/O line. Bit addresses may be specified in two
different formats, the Bit format and the Position format.

The Bit format specifies the desired I/O line using a two-character
hexadecimal number preceded by the letter ‘B’. For example:

Command: $1SB0F

Command Set 4-3

This is an example of the Set Bit (SB) command. The command action is
directed to the address 0F (hexadecimal).

The Position format uses a decimal address preceded by the letter ‘P’. For
example:

Command: $1SP15

This is an example of the Set Position (SP) command. The command action
is directed to the I/O line address 15 (decimal). Note that the last two
command examples produce the same results. The choice of the Bit
notation or Position notation is strictly a matter of user preference.

Logic Convention

Most devices in the D1700 family feature open-collector transistor outputs
to interface directly with solid-state relays. The control input of the relay is
generally connected between the output line and a source of power. With
conventional relays, the output transistor is turned on to sink current through
the relay, turning the relay on. The logic convention used in the D1700
series requires a logical ‘1’ to turn on the relay. This means that the output
voltage measured at the I/O line will be near ground potential (low). This is
an example of negative logic.

The logic convention used to read input data is positive logic. This means
that a ‘high’ voltage potential at the I/O line will be read back as a logical ‘1’.
A low potential will be read back as a logical ‘0’.

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. These commands 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, of course, CR). This allows the use of
spaces (ASCII $20) within the command message for better readability if
desired.

Command Set 4-4

The length of a command message is limited to 25 printable characters. If
a properly addressed module receives a command message of more than
25 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 D1700 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 single ‘*’ 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 25 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 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.

Long Form Responses

When the pound sign ‘ # ‘ command prompt is used, the module will respond
with a ‘long form’ response. This type of response will echo the command
message, supply the necessary response data, and will add a two-

Command Set 4-5

character checksum to the end of the message. Long form responses are
used in cases where 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: $1DI (short form)
Response: *8000

Command: #1DI (long form)
Response: *1DI8000B0 (B0=checksum)

For the D1700 commands that affect the digital outputs, the ‘#’ form of a
command starts a handshaking sequence that must be terminated with an
Acknowledge (ACK) command. (See ACK command)

Checksum

The 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 D1700
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 will calculate the checksum for the
message. If the calculated checksum does not agree with the transmitted
checksum, the module will respond with a ‘BAD CHECKSUM’ error mes­sage and the command will be aborted. If the checksums agree, the
command will be executed. If the module receives a single extra character,
it will respond with a ‘SYNTAX ERROR’ and the command will be aborted.
For example:

Command: $1DI (no checksum)
Response: *8000

Command: $1DIE2 (with checksum)
Response: *8000

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

Command Set 4-6

Command: $1DIE (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: $1DI (short form)
Response: *8000

Command: #1DI (long form)
Response: *1DI8000B0 (B0=checksum)

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 #1DOFF00

Characters: # 1 DO F F 0 0
ASCII hex values: 23 31 44 4F 46 46 30 30

Sum (hex addition) 23 + 31 + 44 + 4F + 46 + 46 + 30 + 30 = 1D3

The checksum is D3 (hex). Append the characters D and 3
to the end of the message: #1DOFF00D3

Example: Verify the checksum of a module response *1DI8000B0

The checksum is the two characters preceding the CR: B0
Add the remaining character values:
*1DI80 00

2A+ 31+ 44+ 49+ 38+ 30+ 30+ 30= 1B0
The two lowest-order hex digits of the sum are B0 which agrees with

the transmitted checksum.

Command Set 4-7

Note that 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.

Table 4.1. 1700 Command Set

Command Definition Typical Typical

Command Response
Message Message

ACK Acknowledge $1ACK *
CB Clear Bit $1CB0C *
CP Clear Position $1CP12 *
DI Digital Input $1DI *8007
DO Digital Output $1DO1234 *
RA Read Assignments $1RA *0F0F
RAB Read Assignment Bit $1RAB01 *O
RAP Read Assignment Pos. $1RAP01 *I
RB Read Bit $1RB0F *1
RD Read Data $1RD *+99999.99
RE Read Event Counter $1RE *0001234
RID Read Identification $1RID *BOILER
RIV Read Initial Value $1RIV *0F0F
RP Read Position $1RP15 *0
RS Read Setup $1RS *31070102
RSU Read Setup $1RSU *31070102
RWT Read Watchdog Timer $1RWT *+00010.00
SB Set Bit $1SB0C *
SP Set Position $1SP12 *
WE Write Enable $1WE *

The following 1700 commands are Write Protected
AIB Assign Input Bit $1AIB0F *
AIO Assign Input/Output $1AIO0F0F *
AIP Assign Input Position $1AIP15 *
AOB Assign Output Bit $1AOB0F *
AOP Assign Output Pos. $1AOP15 *
CE Clear Event Counter $1CE *

Command Set 4-8

EC Event Read & Clear $1EC *0001234
ID Identification $1IDBOILER *
IV Initial Value $1IV0F0F *
RR Remote Reset $1RR *
SU Setup $1SU31070102 *
WT Watchdog Timer $1WT+00010.00 *

The following 1700 commands are used with the special Continuous Input/Output
Modes:
CIA Continuous Input Address $1CIA31 *
CMC Continuous Mode-Change $1CMC *
CMD Continuous Mode Disable $1CMD *
CME Continuous Mode-Edge $1CME *
CMI Continuous Mode-Input $1CMI *
CMT Continuous Mode-Timer $1CMT *
CT Continuous Timer $1CT+00010.00 *
RCM Read Continuous Mode $1RCM *D
RCT Read Continuous Timer $1RCT *+00010.00
RIA Read Input Address $1RIA *31

1700 Command Set

ACKnowledge (ACK)

The ACKnowledge command is a hand-shaking command that may be used
with any command that will affect the the digital outputs such as the Digital
Output (DO) command. It is used to confirm the data sent to a module and
adds another level of data security to guard against transmission errors
when performing output functions.

Command: $1ACK
Response: *

Command: #1ACK
Response: *1ACK2A

The ACK command is used in conjunction with the ‘#’ form of an output
command. For example:

Command: #1DOFFFF
Response: *1DOFFFF06

Note that the command is echoed back with a checksum (06) which is the
case any time the ‘#’ prompt is used. However, in the case of the DO
command, the output data has not been changed at this point. The
command data is echoed back so that the host may verify that the correct

Command Set 4-9

message has been received by the module. If the command data is
confirmed to be correct, the host may then activate the command by issuing
an ACK command:

Command: $1ACK
Response: *

Only at this point will the outputs be affected by the DO command.
If the host detects an error in the response data, it may recover by simply

repeating the original command. For example:

Command: #1DOFFFF
Response: *1DOFFFE05

In ths case the response data does not match the original command,
indicating that the module may have received the command incorrectly due
to noise on the transmission line. However, the erroneous data does not
reach the output since the module must receive an ACK to complete the
command. To correct the error, the host may re-issue the original command:

Command: #1DOFFFF
Response: *1DOFFFF06

This time the response data is correct, and the DO command may be
completed by sending the acknowledgement:

Command: $1ACK
Response: *

Commands that require ACK handshaking are: AIB, AIO, AIP, AOB, AOP,
CB, CP, DO, SB, and SP.

An ACK command used without an associated output command will
generate a COMMAND ERROR.

Assign Input Bit (AIB)
Assign Input Position (AIP)
Assign Output Bit (AOB)
Assign Output Position (AOP)

The Assign Input and Assign Output commands are used to specify the data
direction of an individual I/O line. The Assign Input commands configure an

Command Set 4-10

individual bit to be used as an input to read external signals. The Assign
Output commands configure data bits to be outputs to control external
equipment.

This command configures Bit 05 to be an output:

Command: $1AOB05
Response: *

This command configures Bit 0C to be an input:

Command: $1AIB0C
Response: *

When used with the ‘#’ prompt, the AI and AO commands require an ACK
command from the host to complete the bit assignment:

Command: #1AIB0C
Response: *1AIB0C9A

Command: $1ACK
Response: *

(See Acknowledge (ACK) command for more detail)
The Assign Input Position (AIP) and the Assign Output Position commands

operate in the same manner as the AIB and AOB command except that the
bit positions are specified in decimal (base 10 ) notation.

All of the Assign commands alter the contents of the EEPROM and therefore
must be preceded by a Write Enable (WE) command.

The I/O direction assignments altered by the Assign commands are saved
in EEPROM so that all pin directions are automatically configured when the
device is powered up.

Assign Input/Output (AIO)

The Assign Input/Output (AIO) command is used to configure the data
direction of all data lines at once. The direction data is represented in
hexadecimal notation. A logical ‘1’ indicates that an I/O line will be config­ured as an output. A logical ‘0’ specifies a data input. The length of the hex

Command Set 4-11

data argument will vary according to the number of I/O lines available and
the word length that is setup in the device (see Setup section).

This command configures 16 bits of I/O lines to be outputs:

Command: $1AIOFFFF
Response: *

This command configures 23 lines to be inputs and the LSB as an output:

Command: $1AIO000001
Response: *

Up to 64 I/O lines may be configured at once,:

Command: $1AIOF01234AA5500FF88
Response: *

The ‘#’ form of the AIO command requires an ‘ACK’ to complete the direction
assignments (see ACK command).

The AIO command stores the data direction assignments in EEPROM so
that the I/O lines are configured automatically when the device is powered
up.

The AIO must be preceded by a Write Enable (WE) command.

Clear Bit (CB)
Clear Position (CP)
Set Bit (SB)
Set Position (SP)

The Clear Bit command is used to turn off a single output bit. The CB
command uses hexadecimal notation to address the desired bit:

Command: $1CB0A
Response: *

In this case the hexadecimal bit number 0A is turned off. No other bits are
affected.

If the CB command is used with the ‘#’ prompt, an ACK command is required
to complete the command. For example:

Command Set 4-12

Command: #1CB1F
Response: *1CB1F57

In this case the module has echoed the command along with the response
checksum ‘57’. At this point no output action has taken place. The purpose
of the response message is to allow the host to examine the command
received by the module. Thus, the host may verify that the command was
received without error. Once the host is satisfied with the response data, it
may activate the command by responding with an Acknowledge (ACK)
command:

Command: $1ACK
Response: *

At this point the output bit (B1F in this case) will be turned off.
The CB command will be executed only if the addressed bit has been

previously assigned to be an output. An attempt to clear an input bit will result
in an OUTPUT ERROR message and the command will be aborted. The bit
direction may be assigned with the AI, AO, and AIO commands.

An attempt to clear a bit which does not exist will result in a VALUE ERROR,
indicating an incorrect bit address.

To verify the results of a CB command the output bit value may be read back
with the Read Bit (RB) command.

The Set Bit (SB) command operates exactly like the CB command except
that the addressed bit is turned on.

The Clear Position (CP) and Set Position (SP) commands are similar to the
CB and SB commands except the desired bit is specified with a decimal
address. The following two commands perform exactly the same function:

Command: $1SB0F
Response: *

Command: $1SP15
Response: *

Clear Events (CE)

The Clear Events command clears the event counter to 00000000.

Command Set 4-13

Command: $1CE
Response: *

Note: When the events Counter reaches 9999999, it stops counting. A CE
or EC command must be sent to resume counting.

See also the Events Read & Clear (EC)
command.

Continuous Input Address (CIA)

The CIA command is used to specify the input address of a Continuous Input
module. The address is specified as a two-character code indicating the
ASCII equivalent of the address character:

Command: $1CIA41
Response: *

In this example,the input address is specified as ASCII ‘41’,which is the code
for character ‘A’. If the module is set to Continuous Input mode, it will respond
to data strings containing address ‘A’.

The Continuous Input Address should not be confused with the polled
address as specified with the Setup (SU) Command. Refer to Chapter 6 for
specific uses of the CIA command. An attempt to set the CIA address with
the same value of the polled address will result in an ADDRESS ERROR
response.

The Continuous Input Address is stored in non-volatile memory. The CIA
command must be preceded with a WE command. The address value may
be read back with the Read Input Address (RIA) Command.

Continuous Mode-Change (CMC)
Continuous Mode Disable (CMD)
Continuous Mode-Edge (CME)
Continuous Mode-Input (CMI)
Continuous Mode-Timer (CMT)

The Continuous Mode Commands are used to select and enable Continu­ous Modes as described in Chapter 6. Only one mode may be selected at
any time.

Command Set 4-14

CMC - This output mode produces a data stream each time the input
data lines change.

CMD - Disable all Continuous Modes. This is the normal condition
when D1700 modules are used in a polled system.

CME - Produce an output data stream when the edge-trigger input
receives a positive transition.

CMI - Enable Continuous Input mode which will allow the module to
accept data from a continuous Output module.

CMT - This command enables the Timer Continuous Output Mode. In
this mode a module will output data periodically at a rate specified by the
Continuous Timer (CT) command.

All five Continuous Mode commands require no argument and return no
data:

Command: $1CMD
Response: *

The Continuous Mode selection is saved in non-volatile memory and is
immediately active when power is applied to the module. With the exception
of the CMD command, all of the Continuous Mode commands are write­protected and must be preceded with a WE command. Although the Disable
command is stored in non-volatile memory it is not write-protected in order
to disable a continuous - output module quickly.

The Continuous Mode setup may be read back with the Read Continuous
Mode (RCM) command.

Digital Input (DI)

The Digital input command is used to read the logical state of all of the I/O
lines in parallel. The DI command reads the state of both input and output
lines.

Command: $1DI
Response: *1234

The number of data bits read back is a function of the unit’s word length setup
(see Setup chapter). It is possible to read up to 64 channels:

Command Set 4-15

Command: $1DI
Response: *00FF00EE00CC1234

The rightmost hex digit always represents the least-significant bits, BØØ­BØ3.

If the ‘#’ version of the command is used, do not confuse the checksum with
the digital data.

Digital Output (DO)

The Digital Output command is used to specify the output data to all outputs
at once:

Command: $1DO00FF
Response: *

In this example, 16 bits of output data are specified in parallel. The ‘FF’ data
commands the least significant eight bits (B00 to B07) to turn on. The ‘00’
data turns off the next eight bits (B08 to B0F). This command is appropriate
for devices setup for two words of data.

The hex data length specified in the DO command must match the word
length setup in the D1700 or else the device will send a SYNTAX ERROR.
The following command example may be used with a device set up for eight
words:

Command: $1DO1234567890ABCDEF
Response: *

See the Setup chapter for word length description.
If the DO command is used with the ‘#’ command prompt, an ACK command

is required to complete the output function (see ACK command).
I/O lines assigned to be inputs will ignore data sent by the DO command. No

error message will be generated by outputting data to input channels using
the DO command.

Events Read & Clear (EC)

The EC command is used to read the value of the Events Counter and
automatically clears the count to zero:

Command Set 4-16

Command: $1EC
Response: *0000123

The EC command eliminates a problem that may occur with a Read Events
(RE) and Clear Events (CE) command sequence. Any counts that may
occur between the RE-CE sequence will be lost. The EC command
guarantees that the Event Counter is read and cleared without missing any
counts.

Identification (ID)

The IDentification (ID) command allows the user to write a message into the
nonvolatile memory which may be read back at a later time with the Read
IDentification (RID) command. It serves only as a convenience to the user
and has no other affect on module operation. Any message up to 16
characters long may be stored in memory. Useful information such as the
module location, calibration data, or model number may be stored for later
retrieval.

Message examples:

Command: $1IDBOILER ROOM (module location)
Response: *

Command: #1IDBOILER ROOM (module location)
Response: *1IDBOILER ROOM02

Command: $1ID 12/3/88 (calibration date)
Response: *

Command: $1ID 3125 (model number)
Response: *

The ID command is write-protected.
Since the ID command has a variable length syntax, command checksums
cannot be appended to the message.

Initial Value (IV)

The Initial Value command allows the user to preset the startup condition
of the digital outputs. When the D1700 unit is powered up, it reads data from
the non-volatile memory to set up the initial output conditions. First it reads

Command Set 4-17

the I/O direction data previously specified with the assignment commands.
Then it reads out the Initial Value and performs an internal Digital Output
command. Therefore the digital outputs are set to a known value upon
startup.

The Initial Value is specified with hex data:

Command: $1IV00FF
Response: *

Read Assignment (RA)

The Read Assignment command is used to read back the data direction
configuration of all the I/O lines. The assignments are represented in
hexadecimal notation, with a ‘1’ signifying an output assignment and a ‘0’
indicating an input assignment. The length of the hex data string will vary
according to the number of I/O lines available and the number of words
setup in the device (see Setup section). The LSB is always to the right:

Command: $1RA
Response: *00FF

This response indicates that the most significant eight I/O lines are
configured as inputs and the least significant eight lines are configured as
outputs.

For a device that is setup with a word length of ‘8’, the RA command will read
back the data direction of 64 I/O lines:

Command: $1RA
Response: *00FF00FF88110044

Read Assignment Bit (RAB)
Read Assignment Position (RAP)

The RAB and RAP commands are used to read back the input or output
assignment of a single I/O line.. These commands use Bit or Position bit
addressing to identify the desired bit. The D1700 will return an ‘I’ character
if the bit is assigned to be an input , or an ‘O’ character if the bit is assigned
as an output:

Command: $1RAB0E
Response: *O

Command Set 4-18

Command: $1RAP15
Response: *I

Read Bit (RB)
Read Position (RP)

The Read Bit command is used to read the logical state of any individual
I/O line, input or output. The desired bit is specified with the Bit notation:

Command: $1RB0F
Response: *1

The response data is a ‘1’ or ‘0’ character indicating the state of the I/O line
in positive logic.

Attempting to read a non-existing I/O line will result in a VALUE ERROR.
The Read Position command performs the same function except the data

bit is addressed in Position (decimal) notation:

Command: $1RP15
Response: *1

Note that the last two command examples perform the same function.

Read Continuous Mode (RCM)

The RCM command is used to read back the Continuous Input/Output
Mode:

Command: $1RCM
Response: *D

The response is a single character indicating the Continuous Mode:

C- Continuous Output Change Mode
D- Continuous Output Disabled
E- Continuous Output Edge Trigger
I- Continuous Input
T- Continuous Output Timer

Command Set 4-19

Read Continuous Timer (RCT)

The RCT command is used to read back the time value set by the
Continuous Timer (CT) command:

Command: $1RCT
Response: *+00005.00

The Continuous Timer data is scaled in units of seconds.
The Continuous Timer function is detailed in Chapter 6.

Read Input Address (RIA)

The RIA command reads back the Continuous Input Address stored in non­volatile memory. This command in useful only for modules that are to be
used in Continuous Input Mode (Chapter 6).

Command: $1RIA
Response: *41

The response to the RIA command is the ASCII code of the Continuous
Input Address character. In this example, ‘41’ is the ASCII code for
character ‘A’.

Read Data (RD)

The Read Data (RD) command is used to read analog data from the
devices. Since the Digital I/O products do not acquire analog data, this
command will always result in a fixed response:

Command: $1RD
Response: *+99999.99

Command: #1RD
Response: *1RD+99999.99D9

The RD command is included in the 1700 series to be compatible with other
our products. In many systems that include analog input modules, the host
will acquire data with a software loop containing the RD command. The RD
command is included in digital I/O products so they may be included in the
scanning loop. A proper response from an RD command is a good
indication that the digital I/O device is powered up and running. It also
serves to reset the Watchdog Timer (see the WT command).

Command Set 4-20

Since the RD command is the most frequently used command in a system,
a special truncated form of the command is available to speed up scanning
rates. If a module is addressed without a command, the RD command is
assumed by default:

Command: $1
Response: *+99999.99

Read Event Counter (RE)

The RE command reads the number of events that have been accumulated
in the Events Counter. The output is a seven-digit decimal number:

Command: $1RE
Response: *0000107

The maximum accumulated count is 9999999. When this count is reached,
the Events counter stops counting. The counter may be cleared at any time
with the Events Read & Clear command (EC) or the Clear Events command
(CE).

The Event Count is cleared to zero upon power-up.
The Remote Reset (RR) does not affect the Event Count.
When reading the Event Counter with a checksum, be sure not to confuse

the checksum with the data.

Read Identification

The Read IDentification (RID) command reads out the user data stored by
the IDentification (ID) command. The ID and RID commands are included
as a convenience to the user to store information in the D1700’s nonvolatile
memory.

Command: $1RID
Response: *BOILER ROOM (example)

Command: #1RID
Response: *1RIDBOILER ROOM54 (example)

In this case the RID command has read back the message “BOILER ROOM”

Command Set 4-21

previously stored by the ID command. See ID command.

Read Initial Value (RIV)

The Read Initial Value command is used to read back the Initial Value
stored in the EEPROM. The Initial Value is the output data used to initialize
the D1700 upon power-up. The Initial Value is set with the Initial Value (IV)
command.

Command: $1RIV
Response: *0F0F

The length of the hex data returned is dependant on the specific D1700
model and the number of words in the setup (see Setup chapter)

Read Input Bit (RIB)
Read Input Position (RIP)

The Read Input commands are used to read the logical state of individual
I/O lines. The desired line is specified with either Bit or Position addressing:

Command: $1RIB0F
Response: *1

The module will respond with a ‘1’ or a ‘0’ indicating the state of the specified
I/O line in positive logic.

Command: $1RIP15
Response: *1

Note that in the two command examples the same I/O line is addressed.
The RIB and RIP will read the state of any line whether it is configured as

an input or an output. Therefore it is useful in monitoring the true state of
output data lines.

Read Setup

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

Command Set 4-22

eight hex characters.
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.

Command: $1RSU
Response: *31070102

Command: #1RSU
Response: *1RSU31070102E3

The Read Setup (RS) command performs the same function, and is
included to be compatible with the D1000/2000 series.

Command: $1RS
Response: *31070102

Command: #1RS
Response: *1RS310701028E

Remote Reset

The Remote Reset (RR) command allows the host to perform a program
reset on the module’s microcomputer. This may be necessary if the
module’s internal program is disrupted by static or other electrical distur­bances.

Command: $1RR
Response: *

Command: #1RR
Response: *1RRFF

The RR command is required to modify the baud rate of a module (see
Setup section).

The RR command will not affect the output data or the Event Counter.
The RR command is write-protected.

Command Set 4-23

Read Watchdog Timer

The Read Watchdog Timer (RWT) command reads the time interval
necessary to activate the watchdog timer. The data is scaled in minutes.

Command: $1RWT
Response: *+00010.00 (10 minutes)

Command: #1RWT
Response: *1RWT+00010.0002 (10 minutes)

In each of the two example commands, the response data indicates that the
watchdog timer period is 10 minutes. The watchdog timer value may be set
with the Watchdog Timer (WT) command.

Setup Command (SU)

Each 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.

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

Command: $1SU31070102
Response: *

Command: #1SU31070102
Response: *1SU3107010291

Command Set 4-24

Watchdog Timer (WT)

The Watchdog Timer (WT) command stores a data value in EEPROM
specifying the time-out value of the watchdog timer. The time data is scaled
in minutes:

Command: $1WT+00010.00
Response: *

Command: #1WT+00010.00
Response: *1WT+00010.00B0

These two command examples set the watchdog time value to 10 minutes.
In this example, if the module does not receive a valid command for a period
of 10 minutes, the digital outputs will automatically be forced to the Initial
Value. The purpose of the Watchdog Timer is to force the digital outputs to
a known ‘safe’ value in the event of a host or communications link failure.

The Initial Value is set with the IV command.
The watchdog timer may be disabled by setting the timer value to

+99999.99.
WT command data less than .16 minutes will result in a VALUE ERROR.
The WT command is write protected.

Write Enable

The Write Enable (WE) command must precede commands that are write­protected. This is to guard against accidentally writing over valuable data
in the EEPROM. To change any write protected parameter, 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 4-25

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.

ERROR MESSAGES

All 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. Host computer software can identify an error by the first
character; it is not necessary to read the whole string.

ADDRESS ERROR

There are four ASCII values that are illegal for use as a module address:
NULL ($00), CR ($0D), $ ($24), and # ($23). 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 also produce an error.

An attempt to use the Continuous Input Address (CIA) command to specify
an illegal address or an address identical to the polling address will create
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

Command Set 4-26

channel. More reliable transmissions might be obtained by using a lower
baud rate.

COMMAND ERROR

This error occurs when a 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.

OUTPUT ERROR

An attempt to use a CB, CP, SB, or SP command to set or clear a digital I/
O line that has been assigned as an input will generate an OUTPUT
ERROR.
The Digital Output (DO) command will not generate an OUTPUT ERROR.

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 can range from
0-F.

Command Set 4-27

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 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 (RSU).

The following options can be specified by the SetUp command:

Channel address (124 values)
Linefeeds
Parity (odd, even, none)
Baud rate (300 to 38,400)
Echo
Communication delay (0-6 characters)
Word length

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 Command 5-2

A typical SetUp command would look like: $1SU31070102
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.

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 4 3 2 1 0
binary data: 0 0 1 1 0 0 0 1 = $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 $1SU31070102 , 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: $1SU32070102. When this command is
sent, the module address is changed from ‘1’ to ‘2’.

The module 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

SetUp Command 5-3

to communicate with a module with an unknown address is with the Default
Mode.

The most significant bit of byte 1 (bit 7) must be set to ‘0’. In addition, there
are four ASCII codes that are illegal for use as an address. These codes are
$00, $0D, $24, $23 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 124 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 O66f 7D}
39 9 50 P 67 g 7E ~

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 modules 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 modules 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 ‘0’.

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 0-2 specify the communications baud rate. The baud rate can be
selected from eight 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

SetUp Command 5-5

changed, a module reset must occur. A reset is performed by sending a
Remote Reset (RR) command 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 changing the baud rate of an
RS-232C 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 ‘31070102’. 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: *31070102

Let’s say we wish to change the baud rate to 9600 baud. The code for 9600
baud is ‘010’ (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: $1SU31020180
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: *31020102

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: *

SetUp Command 5-6

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
baud rate is always 300.

Setting a string of RS-232C modules to a new baud rate requires special
consideration. Refer to Chapter 3 for instructions.

Bits 3 and 4

These two bits of byte 2 are not used and should be set to ‘0’.

Table 5.2 Byte 2: Linefeed, Parity and Baud Rate.
BYTE 2
FUNCTION DATA BIT

7654 3210
LINEFEED 1
NO LINEFEED 0
NO PARITY 0 0
NO PARITY 1 0
EVEN PARITY 0 1
ODD PARITY 1 1
NOT USED X X
38400 BAUD 0 0 0
19200 BAUD 0 0 1
9600 BAUD 0 1 0
4800 BAUD 0 1 1
2400 BAUD 1 0 0
1200 BAUD 1 0 1
600 BAUD 1 1 0
300 BAUD 1 1 1

SetUp Command 5-7

Byte 3

This byte contains the setup information for additional communications
options. The default value for this byte is ‘01’.

Echo

When bit 2 is set to ‘1’, the module will retransmit any characters it has
received on the communications line. This option is necessary to ‘daisy­chain’ multiple RS-232C modules. Echo is optional for systems with a single
RS-232C module. Bit 2 must be cleared to ‘0’ on RS-485 models. See
Chapter 3 for a more complete description.

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 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.
BYTE 3
FUNCTION DATA BIT

7654 3210
NOT USED X X X X X
NO ECHO 0
ECHO 1
NO DELAYS 0 0
2 BYTE TIME DELAYS 0 1
4 BYTE TIME DELAYS 1 0
6 BYTE TIME DELAYS 1 1

SetUp Command 5-8

Byte 4

Event Counter Filter

The D1711/1712 contains a programmable digital filter to control the
bandwidth of the Event Counter. The filter is particularly useful when the
Event Counter is used to count transitions from switches or other electro­mechanical contacts. The filter will debounce noisy signals to provide error­free transition counting.

The filter constant is controlled by bits 4 and 5 of byte 4. The selections are
shown in Table 5.4. If no filter is selected, the Event Counter bandwidth is
20kHz. This setting is ideal for electronic signals with clean transitions. To
debounce noisy signals, filter constants of 5, 20, and 50ms are available.
The operation of the digital filter is described in Chapter 2.

Word Length

The D1700 command set is used by many digital I/O devices, ranging from
1 to 64 I/O lines. Many of the commands such as the DO, DI, and RA
commands operate on all of the data lines in parallel. The word length setup
is used to adjust the amount of hex bit data transmitted to and from the
D1700 device. One word of data is defined to be eight bits, represented by
two hexadecimal digits. The number of words required may be adjusted to
a value most appropriate for a specific device.

The word length can vary from 1 to 8 words, specified by bits 0-2. A word
length of 0 is not allowed.

As an example, a D1712 has 15 I/O lines, and a typical setup for this device
would be: 31070102

The ‘02’ indicates that the device is setup for two words, or 16 bits of data.
A typical DO command to this unit would be:

Command: $1DO1234
Response: *

Since the D1712 is setup for two words, it will accept the four digits of hex
data. If the data length is incorrect, an error will be generated:

Command: $1DO12345
Response: ?1 SYNTAX ERROR

SetUp Command 5-9

The word length setup also affects the parallel readback commands such
as:

Command: $1DI
Response: *ABCD

Notice that with a word setup of ‘2’, the DI command returns 2 words of data.
The same effect occurs with the RA and RIV commands.

It is possible to setup a module with a word length that does not correspond
with the physical I/O data width. For example, the D1712 may be setup with
word length = ‘1’. Setup data = 31070101

With this setup, the DI command returns eight bits of data:

Command: $1DI
Response: *CD

The correct DO argument is now two hex digits:

Command: $1DO34
Response: *

A word length of ‘1’ may be appropriate for the D1712 if only eight bits of the
device are used or if maximum communications speed is desired.

Regardless of the word setup, the rightmost hex digit of the bit data is always
the least significant I/O data. The most significant data is appended or
truncated as necessary corresponding to the word length setup.

It is also possible for the word length to be greater than the physical data
width of the device. The D1712 may be setup with a word length of ‘3’:
31070103

In this case, all parallel data values must be 24 bits or six hex digits wide:

Command: $1DO123456
Response: *
Command: $1DI
Response: *003456

The D1712 contains 15 I/O lines. For the DO command, the most significant
nine of the 24 bits will be ignored. The DI command will return with ‘1’ data
for the nine most significant bits.

SetUp Command 5-10

The deliberate use of dummy data may seem wasteful, but it can be useful
for streamlining host software. For example, in a system with a mix of 24 and
15 bit devices, the host software may be simplified by standardizing to word
length ‘3’ for all devices.

The word length setup has no affect on commands using single-bit ‘Bit’ or
‘Position’ addressing.

BYTE 4
FUNCTION DATA BIT

7654 3210
NOT USED X X
NO FILTER 0 0
5ms 0 1
20ms 1 0
50ms 1 1
1 WORD 0001
2 WORDS 0010
3 WORDS 0011
4 WORDS 0100
5 WORDS 0101
6 WORDS 0110
7 WORDS 0111
8 WORDS 1000

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 as 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. For example:

Assume you have a D1711 unit and you wish to set the unit to echo so that
it may be used in a daisy-chain (See Communications). Read out the
current setup with the Read Setup command:

Command: $1RS
Response: *31070102

SetUp Command 5-11

By referring to Table 5.3, we find that the echo is controlled by bit 2 of byte

3. From the RS command we see that byte 3 is currently set to 01. This is
the hexadecimal representation of binary 0000 0001. To set echo, bit 2
must be set to ‘1’. This results in binary 0000 0101. The new hexadecimal
value of byte 3 is 05. To perform the SU command, use the data read out
with the RS command, changing only byte 3:

Command: $1WE (SU is write-protected)
Response: *
Command: $1SU31070502
Response: *

Verify that the module is echoing characters and the setup is correct.
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)
Model Setup Message
D1711 31070102
D1712 31070102
H1750 31070103
H1770 31070108

S1000 Software

Setting up your D1000 module may be greatly simplified by using the setup
program provided in the S1000 software package. The S1000 software
runs on IBM PC’s or compatibles and is free of charge. The setup program
provides a menu-driven operator interface which greatly simplifies the
setup process and decreases the chances of setup errors.

Chapter 6

Continuous Input/Output

The D1711/1712 modules may be setup in special modes which allow them
to communicate without being polled by a host computer. Collectively these
modes are called Continuous Input/Output Modes. In many applications the
burden on the host may be greatly simplified and in some cases the host
may be eliminated altogether.

Continuous Output

A D1711/1712 in continuous mode will produce an output string in the same
format as the response to a #1DI command:

*1DI8000B0

Note that the output message contains the response prompt (*), the module
address (1), the status of the digital I/O lines (8000) and a checksum (B0).
In continuous mode, a D1711/1712 module produces a response to a #1DI
command without actually receiving the command. The output data string
may be triggered in one of three ways:

Timer Mode: In this mode, a software timer is activated in the module with
the Continuous Timer (CT) command. The CT command specifies a time
period that repeats indefinitely. After each timeout, the module will output
the status data. The module will periodically output the digital input data until
the continuous mode is disabled.

Edge-Trigger Mode: In this mode the D1711/1712 will output a data string
when it receives a trigger signal on the B00/EV I/O Pin. The edge trigger
mode will produce an output in response to an external event. It also
provides a means of daisy-chaining several continuous output modules
together.

Change Mode: In this mode the D1711/1712 continuously monitors the
status of the I/O lines. If a change is detected in status, an output data
message is initiated.

Continuous Input

A module setup for continuous input will respond to data produced by a
continuous-output module. The data string from a continuous output
module is interpreted as an output command by a continuous input module.
This allows data to be read at one module and replicated at the outputs of

Continuos Input/Output 6-2

another module without a host computer.

Continuous Input/Output Commands

The D1711/1712 modules contain several commands to setup the continu­ous modes. They are listed here for quick reference. A more complete
description of each command may be found in the Chapter 4.

$1CMD Continuous Mode Disable
$1CMT Enable Timer-Triggered Continuous Output Mode
$1CME Enable Edge-Triggered Continuous Output Mode
$1CMC Enable Change-Triggered Continuous Output Mode
$1CMI Enable Continuous Input Mode
$1RCM Read Continuous Mode Type.
Response is D, T, E, C or I for Disabled, Timer, Edge,

Change or Input respectively.

$1CT Specify Continuous Timer value in seconds.
$1RCT Read Continuous Timer
$1CIA Specify Continuous Address
$1RIA Read Continuous Input Address

Continuous Output Trigger Signal

In order to facilitate daisy-chaining of continuous output modules, each
module will produce an output trigger signal each time it completes an
output data string. The output trigger is a 5 millisecond low pulse which
appears on the Default * pin. The Default * pin is normally an input pin used
to place the module in a known communications setup. This is also true
when a module is set for Continuous Mode. However, when a module
produces a continuous output, the Default * pin momentarily becomes an
output and produces a low-going trigger pulse. This trigger pulse may be
used to trigger another module set in Edge trigger mode. In this manner,
many modules may be daisy-chained together in continuous mode.

Applications

There is a wide variety of system configurations which may be implemented
with the continuous mode modules. It would be impossible to detail every
possible connection. However, a variety of examples will be given to
demonstrate typical usage.

Continuos Input/Output 6-3

A) Timer Mode (Figure 1)

In this configuration, a D1712 module is set to continuously output data to
a host computer or display device. It is not necessary for the host to poll the
D1712 to obtain data. The host computer must have an interrupt-driven
serial input for proper operation.

For this example, we will setup the D1712 to output data every 10 seconds.
(WE commands are not shown but necessary for write-protected com­mands).

1) Setup the D1712 as usual with the setup (SU) command for correct
communications to the host.

Command: $1SU31070102
Response: *

2) Assign the I/O lines of the D1712 to be inputs:

Command: $1AIO0000
Response: *

3) Set the Continuous Timer (CT) for a 10 second interval:

Command: $1CT+00010.00
Response: *

This tells the D1712 to output data continuously in 10 second intervals.

Continuos Input/Output 6-4

4) Activate the continuous output with the Continuous Mode Timer (CMT)
command. This will activate the continuous output data.

5) Every 10 seconds, the D1712 will read the status of its I/O lines and output
the status of those lines as if it was responding to a #1D1 Command:

Response: *1DI1234B2

6) The Continuous Mode may be disabled by the host by sending a
Continuous Mode Disable command:

Command: $1CMD
Response: *

The CMD is not write-protected and a Write Enable (WE) command is not
required.

To avoid communications collisions, the host should wait for a continuous
output response, and then immediately issue the CMD command. In our
current example, the host has 10 seconds to issue the CMD command, so the
likelihood of a collision is remote. It is possible for the host to disable the
continuous mode even if the Continuous Timer is set for 0 seconds. The host
must issue the CMD command immediately after the carriage return from the
D1712 is received. When the D1712 reads a ‘$’or ‘#’ character on the
communications line, it will temporarily halt the continuous mode output and
look for an address character. If the D1712 detects its own address, it will read
and process the rest of the command. Otherwise it will resume the continuous
mode output.

B) Timer Mode With Outputs

This configuration is shown in Figure 1. However, this time the D1712 is setup
with digital outputs. For example, the high-order 7 bits could be configured as
outputs:

Command: $1AIOFF00
Response: *

Setup the Continuous Mode just like example A:

Command: $1CT +00010.00
Response: *

Continuos Input/Output 6-5

Command: $1CMT
Response: *

The D1712 will continuously output the status of the I/O lines, including the
outputs, every 10 seconds.

However, with this setup, the host may respond with DO, SB, CB, or other
output commands to control the digital outputs in response to the input data
or some other control decision.

It is not necessary to disable the continuous mode before issuing the output
command. However, to avoid communications collisions the host command
should be timed to avoid the continuous response from the D1712. The
easiest way to do this is to wait for a continuous output string from the module
and then immediately issue the output command.

Another method of performing output functions is to disable the Continuous
Mode by issuing a Continuous Mode Disable (CMD) command. The D1712
now acts normally and any of the I/O commands may be performed. The
Continuous Mode may be resumed with a Continuous Mode Timer (CMT)
command.

C) Edge-Trigger Mode With Host

The D1712 may be triggered by an external digital signal which will
command the D1712 to read the status of the I/O lines and report the data
(Figure 2).

The external trigger signal is connected to the B00/EV pin of the module.
Since the B00 pin is used for the trigger, it is not available for general-

Continuos Input/Output 6-6

purpose I/O in this application. The trigger input is designed to accept a TTL­level signal, although it will withstand a 0-30V input without damage. The
input may be triggered with a switch by adding a pull-up resistor. (Figure 3)

The module is triggered on a positive-going edge to the B00/EV pin.To
setup the D1712 for edge-trigger mode:

1) Use the setup (SU) command to set the desired communications
parameters. In this case the D1712 will be setup for address ‘2’:

Command: $1SU32070102
Response: *

2) The B00 I/O line must be assigned as an input to accept the trigger signal.
Other I/O lines may be assigned as inputs or outputs depending on the
application:

Command: $2AIOFF00
Response: *

This command assigns B00 through B07 as inputs, and B08 through B0E
as outputs.

Continuos Input/Output 6-7

3) The Continuous Timer (CT) command may be used to specify a delay
time between the Trigger signal and the output data string. This feature is
useful in some applications when multiple modules are tied together which
will be illustrated in other examples. For this and most edge-trigger
applications, set the Continuous timer to 0 seconds:

Command: $2CT+00000.00
Response: *

4) Enable the edge trigger mode with the Continuous Mode Edge-trigger
(CME) command.

5) When the D1712 senses a positive-going trigger on the B00/EV line, it
will perform the equivalent of a #2DI command and output the data:

Response: *2DI1235B3

6) The host may terminate the edge-trigger mode with a Continuous Mode
Disable (CMD) command. Precautions must be used to avoid communica­tions collisions between the host command and responses from the
module. The best method of disabling the continuous mode is to issue the
‘long form’ version of the CMD command:

Command: #2CMD
Response: *2CMD30

The command is issued by the host and then the host looks for the correct
response string to be returned by the D1712. If the correct response string
is detected, then the host knows that the continuous mode has been
disabled. If the correct response string is not received, it may be assumed
that the CMD command collided with response data from the module. The
host simply repeats the CMD command until the correct response is
obtained. Communications collisions are not harmful to RS485 hardware.
However, the host serial input must be able to accept framing errors and
‘noise’ characters gracefully when collisions occur.

Continuos Input/Output 6-8

D) Continuous Output Daisy-Chain With Host (Figure 4)

This configuration uses one module (address 1) in Timer mode which
produces a trigger signal on the Default * line to trigger another module
(address 2) which is set for Edge trigger mode. The third module (address

3) is set-up for edge-trigger mode and receives its trigger signal from the
Default * pin of module #2. Additional edge-triggered modules may be
implemented by connecting the trigger output (Default *) of a module #3 to
the trigger input (B00/EV) of the next module in the series, and this
connection may be repeated for any additional modules. A typical applica­tion will have 1 timer module with any number (up to 123) of edge-triggered
modules.

The net result of this connection is a periodic burst of data from all the
modules without the need for polling by the host. The data stream from this
system would typically look like this:

*1DI1234B2
*2DI0001AA
*3DIFFFF02

Each data string is terminated by a carriage return. Note that the module
address is transmitted with the data to easily determine the origin of the
data.

Continuos Input/Output 6-9

The easiest way of setting up a system like this is to install the modules and
operate them as a polled system first. Once the wiring and the operation of
all the modules is established, the string may be set for Continuous Mode.
First, set up all the Edge Triggered modules as described in Example C. The
last step is to setup the Timer module as described in Example A. The CT time
specified in the Timer module must be long enough to allow all the modules
to respond. If the CT time is too short, module #1 will start to output data before
module #3 has finished, resulting in a communications collision.

In some cases, especially if a large number of modules are connected in a
string, the amount of data transmitted may overload the serial port buffer of
the host. In this case, the data may be slowed down by specifying a finite
amount of time in the Continuous Timer (CT) of each edge-triggered module.
A module in Edge trigger mode will delay the output data after it is triggered
by the amount specified in CT.

The host may disable the continuous output data by sending a Continuous
Mode Disable command to the timer module:

Command: #1CMD
Response: *1CMD2F

The host should repeat the CMD until the proper response is obtained. After
the timer mode is disabled, the string of modules may be polled by the host.
To return to continuous output operation, enable the continuous mode of the
Timer module:

Command: $1CMT
Response: *

E) Change Mode (Figure 5)

Continuos Input/Output 6-10

A D1712 module set up for change mode will output a data string if one of
its digital input lines has changed state. The module will output the data
string reporting the new state of the inputs.

To setup the D1712 for change mode:
Assign the desired I/O lines to inputs:

Command: $1AIO00FF
Response: *

Note that not all lines are required to be inputs. In this example, digital I/O
lines B00-B07 are set to outputs and B08-B0E are set to inputs.

For this example, set the Continuous Timer to zero:

Command: $1CT+00000.00
Response: *

Set the module to Continuous Mode:

Command: $1CMC
Response: *

The D1712 will continually scan the Digital I/O lines to detect any changes
of state. If a change is found, the new state of the I/O lines is reported to the
host:

*1DI01FFD5

After the response is transmitted, the D1712 will resume scanning the I/O
lines.

The host may disable the continuous output mode by sending a CMD
command:

Command: #1CMD
Response: *1CMD2F

The module may now be interrogated with the normal command -response
sequence. This method is useful when the host is required to produce an
output response to a change in the input status. The host may control the
digital output lines (in this case B00-B07) with normal I/O commands. After

Continuos Input/Output 6-11

the control function is completed, the D1712 may be returned to Continuous
Mode with the CMC command.

The change mode is ideal in applications where the state of the digital inputs
is expected to change infrequently. Inputs such as security switches, fire
detectors, alarm switches, etc. are not expected to change but must be
detected by the host computer. By using a D1712 in change mode, the host
may be alerted to a change in input status on an interrupt basis thereby
saving computer time scanning inputs that are static.

F) Change Mode With Multiple Modules: (Figure 6)

It is possible to configure two or mode modules to Continuous Output
Change mode on the same serial port.

This configuration may be used to extend the number of inputs monitored.
The one drawback to this connection is that there is no means of avoiding
a communications collision if two modules attempt to output data messages
at exactly the same time. This will result in communications errors.
Theoretical considerations aside, this type of connection may be very
useful if the following guidelines are adhered to:

1) The inputs being scanned are primarily static. This is usually the case
when monitoring security and alarm type of inputs where the change of an
input indicates an extraordinary event. This cuts down the likelihood that
two events would occur at the same time.

Continuos Input/Output 6-12

2) Checksums and parity must be used to detect communications errors
caused by data collisions.

3) The host input port should be setup so that any activity on the input lines
is evidence that a change in input status has occurred. This will cover the
unlikely possibility that two modules are responding at exactly the same
time. In this case the host may disable the Continuous Mode and poll the
modules directly to read the input lines.

4) Use the highest baud rate possible to reduce the likelihood of collisions.

5) The Continuous Timer may be used to limit responses from a module.
This particularly useful if an input is likely to turn on and off quickly and
constantly, causing a continuous stream of data from one module. The CT
command may be used to set a ‘dead time’ after a module has produced
an output response:

Command: $1CT+00005.00
Response: *

With the Continuous Timer set to 5 seconds, module #1 will pause for 5
seconds after each response before resuming scanning the digital I/O lines.
This prevents the module from hogging the communications bus in re­sponse to continuously changing input lines.

G) Continuous Input Mode

The D1711/1712 modules may be set to a special mode called Continuous
Input Mode which allows the module to respond to data transmitted by
another module. A module in Continuous Input Mode may be paired with
a module in Continuous Output Mode to provide digital data transfer without
a supervisory host. Figure 6 shows the simplest connection.
(Figure 7)

Continuos Input/Output 6-13

Module #1 is setup in Continuous Output Timer Mode as described in
Example A. Module #1 will read the state of the digital inputs and produce
data messages on the communications bus. In this application, setting the
Continuous Timer to zero will produce the fastest response to input
changes.

Module #2 is setup for Continuous Input Mode. The digital I/O lines of
module #2 are assigned as outputs. In continuous input mode, module #2
will use the data from module #1 as a command to control the digital outputs.
The net effect is that the outputs of module #2 are controlled directly by the
inputs of module #1.

For example, an output message from module #1 might look like:

*1DIA0A059 (59 is checksum)

Module #2 in Continuous Input mode will interpret this data as a Digital
Output command. Internally, the continuous input module will translate this
data and perform the same function as:

$1DO5F5FAD (AD is checksum)

Note that the original data ‘A0A0’ is complemented to ‘5F5F’. This is
necessary so that a high input at module #1 appears as a high output at
module #2. As a result, the state of the digital inputs on module #1 is
recreated at the digital outputs of module #2.

Since module #1 is continually outputting data on the communications lines,
any changes in the state of the digital inputs on module #1 will be transmitted
to module #2 and the output lines will change to reflect the new state.

To setup module #2 for Continuous Input Mode:

1) Setup the module for an address different from the Continuous Output
module. In this example, the Continuous Output module is setup for address
‘1’. The Continuous Input module will be setup for address ‘2’:

Command: $1SU32070102
Response: *

Any address may be used for the Continuous Input module as long as it is
different from module #1.

Continuos Input/Output 6-14

The communications setups for both modules must match. They must be
setup with identical baud rate and parity settings. Also, the word length
setup must be identical.

2) Assign the digital I/O lines to be outputs:

Command: $2AIOFFFF
Response: *

3) The Continuous Input module must be assigned a Continuous Input
Address (CIA). This address is different from the normal communications
address. This address is necessary so that the continuous input module
may selectively read data on the communications bus. The full purpose of
the CIA will be demonstrated in the next few examples. In this case, module
#2 is setup to respond to data from module #1. Character ‘1’ or ASCII ‘31’
is the Continuous Input Address:

Command: $2CIA31
Response: *

The input address ‘31’ is stored in nonvolatile memory. It can be read back
with the Read Input Address command:

Command: $2RIA
Response: *31

4) Enable the Continuous Input Mode with the Continuous Mode Input
command:

Command: $2CMI
Response: *

The Continuous mode is saved in nonvolatile memory.
After the Continuous Input module has been setup, it may be connected to

the continuous output module as a stand-alone pair. Since all setup data is
stored in nonvolatile memory, the input-output pair will initialize automati­cally upon power-up. No host is necessary for the continuous input-output
function.

H) Multiple Continuous Input/Output

Figure 8 shows a system, with two modules set for continuous output mode
and two modules set for Continuous Input Mode: (Figure 8)

Continuos Input/Output 6-15

This system is similar to example E except that 2 input-output module pairs
share the same communications line. Modules #1 and #2 are setup for
continuous output as detailed in example B. This pair of D1712’s constantly
read the state of their respective digital I/O lines and output the data on the
communications bus. A typical output data stream would be:

*1DI8123B6 (B6 is checksum)
*2DIA0A0CB (CB is checksum)

Module #3 is set for Continuous Input mode with the Continuous Input
Address (CIA) equal to ASCII ‘31’ or character ‘1’. This module will pick off
the output data from module #1 and use the data as a command to set its
output lines. Module #3 will ignore the data from module #2.

Module #4 is set for Continuous Input mode and its Continuous Input
Address (CIA) is equal to ASCII ‘32’ or character ‘2’. It examines the data
on the communications bus and responds only to data containing the
address ‘2’. Therefore the outputs of module #4 will follow the inputs of
module #2. In theory, up to 124 pairs of modules may be linked together on
a single communications bus.

I) Bidirectional Continuous Input/Output

To provide bidirectional data transfer from one location to another, simply
use two pairs of modules and two communications links: (Figure 9)

Continuos Input/Output 6-16

J) Multiple Outputs

The output data from a Continuous Output module may be used to
control more than one continuous input module by assigning the
correct Continuous Input Addresses (CIA): (Figure 10)

Continuos Input/Output 6-17

In this system, module #1 is set for Continuous Output mode. Modules 2,
3 & 4 are setup for Continuous Input. The three Continuous Input modules
are all setup with a Continuous Input Address (CIA) of ASCII 31 or character
‘1’. This means that each of these three modules will accept the data from
module #1 as an output command. The outputs of modules 2, 3 and 4 will
replicate the input data of module #1.

Continuous Input Protocol Notes

A module in continuous input mode will respond to data in the form of:

*1DI80F096

This is typical of a data string that may be produced by a continuous output
module. The ‘1’ denotes the address of the module producing the data
stream. The Continuous Input Module will respond to this data only if it is
programmed to read data from module #1. The Continuous Input Address
(CIA) is used to specify which data strings will be examined by the
Continuous Input module. The CIA command is used to specify the ASCII
code for the address character. In this case, to allow the module to respond
to data with the address tag ‘1’, use the command:

Command: $2CIA31
Response: *

The number ‘31’ is the ASCII code for character ‘1’.
An important consideration in constructing a continuous input/output sys-

tem is to make sure that all modules tied to the communications bus have
unique address as specified by the SU command. This allows an intelligent
host to use the modules in a normal polled manner. This greatly simplifies
setup and debugging. The Continuous Input Addresses (CIA) may be set
to any value independent of the polled address.

Chapter 7

Power Supply

D1711/D1712 modules may be powered with an unregulated +10 to
+30Vdc. Power-supply ripple must be limited to 5V peak-to-peak, and the
instantaneous ripple voltage must be maintained between the 10 and 30
volt limits at all times. 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.

The D1711/D1712 modules employ an on-board switching regulator to
maintain good efficiency over the 10 to 30 volt input range; therefore the
actual current draw is inversely proportional to the line voltage. The D1711/
D1712 consume a maximum of .75 watts and this figure should be used in
determining the power supply current requirement. For example, assume
a 24 volt power supply will be used to power four modules. The total power
requirement is 4 X .75 = 3 watts. The power supply must be able to provide
3 / 24 = 0.125 amps.

In some cases, a small number of modules may be operated by “stealing”
power from a host computer or terminal. Many computers provide a +15 volt
output on the RS-232C DB-25 connector.

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.

The D1711/D1712 modules are protected against power supply reversals.
The H1750/H1770 boards are powered by +5Vdc ±0.25V @ 30mA max.

(not including any I/O module requirements.

Chapter 8
Troubleshooting

Symptom: RS-232 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 between +10 and
+30Vdc.

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

3 Connect the module to the host computer and power-up each device
(module and computer) then using a voltmeter measure the voltage be­tween RECEIVE and GND. This voltage should be approximately - 10Vdc.
Repeat the measurement between TRANSMIT and GND terminals and
confirm the voltage value to be approximately -10Vdc. If either of the two
readings is approximately 0.0Vdc then the communications data lines are
wired backwards. Proper communications levels on both TRANSMIT and
RECEIVE terminals should idle at -10Vdc.

4 If you are using a serial communications converter (A1000) ensure that
the communications Baud Rate switch is set to the proper Baud Rate value.

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

6 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).

7 If the module(s) are being used in a RS-232 daisy-chain communica­tions configuration then ensure that the “Echo Bit” is enabled in the
setup(SU) message of each module.

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.

Symptom: RS-485 Module is not responding to commands

1 Perform steps 1, 2, 4, 5 and 6 listed above.

Troubleshooting 8-2

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

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

4 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.

Symptom: D1711, D1712 events counter not counting properly.

1 Check that the frequency of the signal, being counted is less than 60Hz.
2 Ensure that the signal levels are swinging below +1.0Vdc and greater

than +3.5Vdc.

Troubleshooting 8-3

Appendix A

ASCII Table

Table of ASCII characters (A) and their equivalent values in
Decimal (D), Hexadecimal (Hex), andBinary.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

ASCII Table A-2

A D Hex Binary D Hex Binary
“ 34 22 00100010 162 A2 10100010
# 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
>623E00111110 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 Table 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
u 117 75 01110101 245 F5 11110101

ASCII Table A-4

A D Hex Binary D Hex Binary
}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

H1770 64 Channel Digital I/O Board

The H1770 Digital I/O interface is designed to provide remote I/O capability
for computers, modems, and other devices with standard serial ports.
Commands communicated over standard RS-232 or RS-485 links may be
used to control or read up to 64 digital I/O channels.

The H1700 is designed to interface to industry-standard solid-state relay
racks. Up to four 16-channel racks may be connected to the H1770 with
ribbon cable connectors.

The 64 I/O channels may be configured to be inputs or outputs in any
combination designated by the user. The input/output configuration may be
changed at any time through the communications port. The I/O assign­ments are saved in nonvolatile memory and are automaticly loaded when
the unit is powered up.

Getting Started
RS-232, RS-485 Selection

The H1770 contains drivers to connect to either RS-232 or RS-485 ports.
The H1770 must be configured to the desired interface before it is con­nected to the host. The H1770 has a 12-pin header near the edge of the
board marked RS-232/RS-485. To configure the board for RS-232, make
sure the three jumpers are installed adjacent to the RS-232 label. To
configure the board for RS-485, make sure the jumpers are adjacent to the
RS-485 label.

Pin Connections

The host interface connection is wired to the six-pin terminal plug:
Pin 1: +5V This is the power supply connection for the board. The power

supply must provide +5V +/- 5% at 100 mA.
Pin 2: DEFAULT* This pin is normally left open or pulled high to +5V. When

grounded, the board assumes the default communications setup of 300
baud, any address, no parity (See Chapter 1).

Pin 3: DATA/TX This pin is a serial port connection. If the board is
configured for RS-485, this pin is the DATA connection. For RS-232, pin 3
is the Transmit output from the H1770.

Pin 4: DATA*/RX This pin is a serial port connection. If the board is
configured for RS-485, this is the DATA*, or the negative data connection.
For RS-232, this is the receive input of the H1770.

H1770 B-2

Pin 5: CONT* This pin is normally left open or pulled up to +5V. When
grounded, the H1770 will be in Continuous Mode.

Pin 6: GND This is the power supply ground connection. It is also the signal
ground for the serial port.

Output Connections

The digital I/O connections are made through the four ribbon cable connec­tors. The output connections are made to be compatable with industry­standard 16-channel solid-state relay racks. The connector nearest the edge
of the board (J2) is wired to the lowest-order 16 bits.

J2

Pin Signal
17 B0F
19 B0E
21 B0D
23 B0C
25 B0B
27 B0A
29 B09
31 B08
33 B07
35 B06
37 B05
39 B04
41 B03
43 B02
45 B01
47 B00

All even pins are connected to GND
All other pins are no connection.

J3

Pin Signal
17 B1F
19 B1E
21 B1D
23 B1C
25 B1B
27 B1A
29 B19
31 B18
33 B17
35 B16
37 B15
39 B14
41 B13
43 B12
45 B11
47 B10

All even pins are connected to GND
All other pins are no connection.

J4

Pin Signal
17 B2F
19 B2E
21 B2D
23 B2C
25 B2B
27 B2A
29 B29
31 B28
33 B27
35 B26
37 B25
39 B24
41 B23
43 B22
45 B21
47 B20

H1770 B-3

Even pins 18-50 are connected to GND
All other pins are no connection.

J5

Pin Signal
17 B3F
19 B3E
21 B3D
23 B3C
25 B3B
27 B3A
29 B39
31 B38
33 B37
35 B36
37 B35
39 B34
41 B33
43 B32
45 B31
47 B30

Even pins 18-50 are connected to GND
All other pins are no connection.

H1770 B-4

Appendix C

H1750 24-Channel Digital I/O Board

The H1750 is designed to interface directly to an Opto-22 16 or 24 channel
solid-state relay backplane or equivalent backplanes with the standard pin­out.

Hook-Up:
Plug the H1750 into the backplane header. Be sure the board is centered
over the header and latch the board to the header.

The H1750 contains line drivers for both RS-232 and RS-485. Select the
desired communications link with the three shorting bars near the edge of
the H1750. Move the three shunts to the ‘RS-232’ position to select RS-232.
Move the three shunts to the ‘RS-485’ position to select RS-485.

If RS-232 is selected, the DATA/TX pin on the 6-pin connector is the
transmit output pin. The DATA*/RX pin is the receive input.

If RS-485 is selected, connect the Data (Data +) line to the DATA/TX pin and
the Data* (Data -) line to the DATA*/RX pin.

The H1750 is powered by a regulated 4.75 to 5.5V power supply connected
to the GND and +5 Vdc pins. For proper operation, relays used in a
backplane should be +5V types.

I/O lines are connected to the odd-numbered pins on the header connector.
The odd-numbered pins are closest to the edge of the board with the square
pad being #1. All even-numbered pins are connected to ground.

Pin Connections

The host interface connection is wired to the six-pin terminal plug:
Pin 1: +5V This is the power supply connection for the board. The power

supply must provide +5V +/- 5% at 100 mA.
Pin 2: DEFAULT* This pin is normally left open or pulled high to +5V. When

grounded, the board assumes the default communications setup of 300
baud, any address, no parity (See Chapter 1).

Pin 3: DATA/TX This pin is a serial port connection. If the board is
configured for RS-485, this pin is the DATA connection. For RS-232, pin 3
is the Transmit output from the H1750.

H1750 C-2

Pin 4: DATA*/RX This pin is a serial port connection. If the board is
configured for RS-485, this is the DATA*, or the negative data connection.
For RS-232, this is the receive input of the H1750.

Pin 5: CONT* This pin is normally left open or pulled up to +5V. When
grounded, the H1750 will be in Continuous Mode.

Pin 6: GND This is the power supply ground connection. It is also the signal
ground for the serial port.

Output Connections

The digital I/O connections are made through the connector. The output
connections are made to be compatable with industry-standard 16 or 24­channel solid-state relay racks. The 50-pin ribbon connector near the edge
of the board is wired as follows.

Pin Signal
1 B17
3 B16
5 B15
7 B14
9 B13
11 B12
13 B11
15 B10
17 B0F
19 B0E
21 B0D
23 B0C
25 B0B
27 B0A
29 B09
31 B08
33 B07
35 B06
37 B05
39 B04
41 B03
43 B02
45 B01
47 B00

All even pins are connected to GND
All other pins are no connection.

Appendix D

1700 Series Specifications

1700 Series Specifications (typical @ +25°C and nominal power supply
unless otherwise noted)

H1750/H1770 Digital Input/Output Boards

H1750: 24 digital input/output bits with RS-232 or RS-485 output.
H1770: 64 digital input/output bits with RS-232 or RS-485 output.

• User can define any bit as an input or an output.

• Inputs/Outputs can be read/set individually or in parallel.

• Input voltage levels: 0-10V without damage.

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

• Outputs: 0-10V, 15mA max. load.

• Power requirements: +5Vdc ±0.25V @ 30mA max. (not including I/O

modules requirements)

• User selectable RS-232/RS-485 Communications.

D1700 Digital Input/Output Modules

D1711: 15 digital input/output bits with RS-232 output.
D1712: 15 digital input/output bits with RS-485 output.

• User can define any bit as an input or an output.

• 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.

• Events counter: Up to 10 million positive transitions at bandwidths

of 20Hz, 50Hz, 200Hz and 20KHz.

• Power requirements: Unregulated +10V to +30Vdc, 0.75W max.

• Internal switching regulator.

• Protected against power supply reversals.

Communications

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

• Up to 124 multidrop boards per host communications port.

• User selectable channel address.

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

1 stop bit.

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

38400.

• ASCII format command/response protocol.

• Can be used with a “dumb” terminal.

• Parity: odd, even, none.

1700 Specifications D-2

• All communications setups (address, baud rate, parity) stored in

nonvolatile memory using EEPROM.

• Transient suppression on RS-485 Communications lines.

• Communications error checking via checksum.

• Communications distance up to 4,000 feet.

Digital

• 8-bit CMOS microcomputer.

• Nonvolatile memory storage for start up values eliminates software

initialization.

Environmental

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

Storage -25°C to +85°C.

Relative Humidity: 0 to 95% noncondensing.

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.

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