OPTO 22 AC7A User manual

AC7A/B USER’S GUIDE
Form 0233-160920—September 2016
43044 Business Park Drive • Temecula • CA 92590-3614
Phone: 800-321-OPTO (6786) or 951-695-3000
Fax: 800-832-OPTO (6786) or 951-695-2712
www.opto22.com
Product Support Services
800-TEK-OPTO (835-6786) or 951-695-3080
Fax: [phone]
Email: suppor[email protected]
Web: support.opto22.com

AC7A/B User’s Guide
ii
AC7A/B User’s Guide
Form 0233-160920—September 2016
Copyright © 1997–2012 Opto 22.
All rights reserved.
Printed in the United States of America.
The information in this manual has been checked carefully and is believed to be accurate; however, Opto 22 assumes no
responsibility for possible inaccuracies or omissions. Specifications are subject to change without notice.
Opto 22 warrants all of its products to be free from defects in material or workmanship for 30 months from the
manufacturing date code. This warranty is limited to the original cost of the unit only and does not cover installation, labor,
or any other contingent costs. Opto 22 I/O modules and solid-state relays with date codes of 1/96 or newer are guaranteed
for life. This lifetime warranty excludes reed relay, SNAP serial communication modules, SNAP PID modules, and modules
that contain mechanical contacts or switches. Opto 22 does not warrant any product, components, or parts not
manufactured by Opto 22; for these items, the warranty from the original manufacturer applies. Refer to Opto 22 form
1042 for complete warranty information.
Wired+Wireless controllers and brains are licensed under one or more of the following patents: U.S. Patent No(s). 5282222,
RE37802, 6963617; Canadian Patent No. 2064975; European Patent No. 1142245; French Patent No. 1142245; British Patent
No. 1142245; Japanese Patent No. 2002535925A; German Patent No. 60011224.
Opto 22 FactoryFloor, groov, Optomux, and Pamux are registered trademarks of Opto 22. Generation 4, groov Server,
ioControl, ioDisplay, ioManager, ioProject, ioUtilities, mistic, Nvio, Nvio.net Web Portal, OptoConnect, OptoControl,
OptoDataLink, OptoDisplay, OptoEMU, OptoEMU Sensor, OptoEMU Server, OptoOPCServer, OptoScript, OptoServer,
OptoTerminal, OptoUtilities, PAC Control, PAC Display, PAC Manager, PAC Project, PAC Project Basic, PAC Project Professional,
SNAP Ethernet I/O, SNAP I/O, SNAP OEM I/O, SNAP PAC System, SNAP Simple I/O, SNAP Ultimate I/O, and Wired+Wireless
are trademarks of Opto 22.
ActiveX, JScript, Microsoft, MS-DOS, VBScript, Visual Basic, Visual C++, Windows, and Windows Vista are either registered
trademarks or trademarks of Microsoft Corporation in the United States and other countries. Linux is a registered
trademark of Linus Torvalds. ARCNET is a registered trademark of Datapoint Corporation. Modbus is a registered trademark
of Schneider Electric, licensed to the Modbus Organization, Inc. Wiegand is a registered trademark of Sensor Engineering
Corporation. Allen-Bradley, CompactLogix, ControlLogix, MicroLogix, SLC, and RSLogix are either registered trademarks or
trademarks of Rockwell Automation. CIP and EtherNet/IP are trademarks of ODVA.
groov includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (http://www.openssl.org)
All other brand or product names are trademarks or registered trademarks of their respective companies or organizations.
Opto 22
Automation Made Simple.

2AC7A/B User’s Guide
TABLE OF CONTENTS
Welcome ................................................................................................... 4
Introduction .............................................................................................. 5
Description ........................................................................................................................................ 5
Features .............................................................................................................................................. 5
Specifications ................................................................................................................................... 6
Dimensions ........................................................................................................................................ 6
Installing the AC7A/B for use with Opto 22’s Optomux I/O .................... 7
Equipment Required for Installation ........................................................................................ 7
Mounting the AC7A/B ................................................................................................................... 7
Connecting AC Power to the AC7A/B ....................................................................................... 8
Connecting the AC7A/B to Your PC .......................................................................................... 9
Setting the AC7A/B RS-232 Jumpers
(First group - near the 25-pin RS-232 connector) ............................................................ 12
Setting the AC7A/B RS-422/485 Jumpers (Groups B and C) .......................................... 13
Connecting the AC7A/B to the Optomux Network ........................................................... 14
Apply AC Power ............................................................................................................................ 15
Communication LEDs .................................................................................................................. 15
Installing the AC7A/B for use with devices other than
Opto 22’s Optomux I/O .......................................................................... 16
Overview ......................................................................................................................................... 16
Equipment Required for Installation ..................................................................................... 16
Mounting the AC7A/B ................................................................................................................ 16
Connecting AC Power to the AC7A/B .................................................................................... 17
Connecting the AC7A/B to a PC or Other RS-232 Device .............................................. 18
Setting the AC7A/B RS-232 Jumpers
(First group - near the 25-pin RS-232 connector) ............................................................ 20
RS-232 Handshaking Signals for Hardware Flow Control ...................................... 22
Setting the AC7A/B RS-422/485 Jumpers (Groups B and C) .......................................... 23
Connecting the AC7A/B to an RS-422/485 Device ........................................................... 24
Applying AC Power ..................................................................................................................... 26
Communication LEDs .................................................................................................................. 26
WELCOME

AC7A/B User’s Guide 3
WELCOME
Additional Technical Information ........................................................ 27
General Notes ................................................................................................................................ 27
Two-Wire RS-485 Mode ............................................................................................................ 28
Using Multiple AC7A/B Units on One Link .......................................................................... 30
Background ........................................................................................................................... 30
Description ............................................................................................................................. 30
Setup ......................................................................................................................................... 31
Biasing ...................................................................................................................................... 31
Termination ............................................................................................................................. 31
Wiring and Related Jumpers ............................................................................................. 31
Additional Jumpers ..............................................................................................................31
Commonly Used RS-232 Signals ............................................................................................. 32
Using Protective Ground on AC7A/B ............................................................................. 33
Biasing and Terminating RS-422/485 ................................................................................... 33
Communication Jumpers ................................................................................................... 34
Troubleshooting ........................................................................................................................... 35
Glossary of Terms ......................................................................................................................... 36
RS-422/485 Cable Specifications ........................................................................................... 37
Appendix A: AC7A/B DB9 (J2) Connection Pinout ................................ 38
Product Support ..................................................................................... 39

4AC7A/B User’s Guide
WELCOME
WELCOME
OVERVIEW
Opto 22’s AC7A/B is an external, standalone, adapter card which converts RS-232 serial communication
to RS-422/485 serial communication. The AC7A/B has optical isolation between its RS-232 port and its
RS-422/485 port, with full transient protection on the RS-422/485 lines. The AC7A/B is an open chassis circuit
board, and is designed to be mounted inside a protective enclosure (protective enclosure not included.)
The converter operates as a full duplex device with transmission speeds up to 38,400 baud for distances up to
5,000 feet using two twisted pairs and a ground wire. Only “REV L” boards and above (AC7A) and “Rev C” boards
and above (AC7B), can be used up to 115,200 baud. Earlier revision boards will operate up to 38,400 baud only.
ABOUT THIS MANUAL
This manual is organized as follows:
•Introduction
•Installing the AC7A/B for use with Opto 22’s Optomux I/O
•Installing the AC7A/B for use with Devices other than Opto 22’s Optomux I/O
•Additional Technical Information
•Appendix A: AC7A/B Connection Pinout
•Product Support
Updated: 01/22/04

AC7A/B User’s Guide 5
INTRODUCTION
DESCRIPTION
The AC7A/B is an external, standalone, adapter card which converts RS-232 serial communication to RS-422/485
serial communication. The AC7A/B has optical isolation between its RS-232 port and its RS-422/485 port, with full
transient protection on the RS-422/485 lines. The AC7A/B is an open chassis circuit board, and is designed to be
mounted inside a protective enclosure (protective enclosure not included.) The converter operates as a full duplex
device with transmission speeds up to 38,400 baud for distances up to 5,000 feet using two twisted pairs and a
signal ground wire. Revision L and newer AC7A/B’s can operate at up to 115,200 baud. The maximum distance for
115,200 baud rate is 3,000 feet.
Note: See the solder (non-component) side of the circuit board for the revision number. An example is “001782L”
where “L” is the revision letter.
FEATURES
• RS-422/485 balanced line drivers.
• Multidrop capability on the RS-422/485 communication lines.
• Baud rates up to 38,400 baud (up to 115,200 baud for revision L and more current).
• Up to 5,000 feet maximum cable length at 38,400 baud (3,000 feet maximum cable length at 115,200 baud).
• Bi-directional CTS and RTS handshaking lines.
• Optically-isolated up to 4,000 volts between the RS-232 and RS-422/485 lines.
• RS-422/485 lines have transient protection.
• LED indicators for transmit, receive, RTS, CTS, and power.
• On-board power supply.
• Jumper configurable termination and biasing for RS-422/485 lines.
INTRODUCTION

6AC7A/B User’s Guide
SPECIFICATIONS
Power Requirements
AC7A
AC7B 115 VAC ± 10 VAC @ 50-60 Hz 220 VAC ± 20 VAC @ 50-60 Hz
Power Consumption 0.1 amps @ 115 VAC
5 watts (dissipation)
Operating
Temperature Range 0° C to 70° C 0 to 95% humidity(non-condensing)
Optical Isolation 4,000 VAC between RS-232 and RS-422/485
RS-232 Interface 25-pin, DB-25 female connector
RS-422/485 Interface Screw terminals or 9-pin, DB-9 female connector
Baud Rate Up to 38,400 baud (115,200 baud in Rev. L and later)
RS-232 Distance Up to 50 feet
RS-422/485 Distance Up to 5,000 feet at 38,400 baud (3,000 feet at 115,200 baud)
Communications RS-422/485 full duplex over two twisted pairs and a signal ground.
Additional twisted pairs for RTS and CTS. Also supports RS-485
2-wire mode. This requires user to build a custom RS-232 cable.
Indicators Transmit, receive, RTS, CTS, and power.
DIMENSIONS
Figure 1-2: AC7A/B Card Dimensions
INTRODUCTION

AC7A/B User’s Guide 7
INSTALLING THE AC7A/B FOR USE
WITH OPTO 22’S OPTOMUX I/O
This section gives instructions for installing the AC7A/B adapter card for connecting an Optomux network in
4-wire RS-422/485 mode with a PC.
If you are using the AC7A/B card to communicate with equipment other than Opto 22’s Optomux I/O, please see
“Installing the AC7A/B for use with devices other than Opto 22’s Optomux I/O” later in this document. If you would
like more detailed information, please see “Additional Technical Information”.
EQUIPMENT REQUIRED FOR INSTALLATION
• Medium size flat-blade screwdriver
• Wire stripper
• Variety of color-coded wires and cables:
- #22 or #24 gauge twisted-pair cable for communication cables
- #18 gauge for power connections.
MOUNTING THE AC7A/B
The AC7A/B adapter card may be mounted in any position on any flat surface. The AC7A/B is supplied with
3/4” standoffs. All of the standoffs should be secured using #6 mounting hardware to provide maximum physical
strength. Sufficient space should be left around the AC7A/B for serial communication cables and for power wiring.
Figure 2-1 shows the dimensions of the AC7A/B adapter card.
INSTALLATION

8AC7A/B User’s Guide
Figure 2-1: AC7A/B Card Dimensions
CONNECTING AC POWER TO THE AC7A/B
Caution: Make sure that power is OFF while making or removing all connections to the AC7A/B and Optomux.
For safety purposes, a plastic insulating cover is provided for the power terminal block, and shouldbe installed after
power wiring is completed.
The AC7A/B has a terminal strip with three screw terminals for AC power. The AC power, which is supplied to the
AC7A/B, should have three wires, two for AC power and one for earth ground (usually colored green). Connect the
wire for earth ground (usually colored green) to the center screw terminal which is labeled GND. Connect theother
two wires to the terminals marked AC, one wire per terminal. The polarity of the AC power wires withrespect to the
AC screw terminals on the power connector of the AC7A/B does not matter.
If using a standard, 3-conductor power cord with a three-pronged plug, it should be at least #18 gauge wires or
larger. On one end should be the three-pronged plug; the other should have three wires with approximately
1/4” (6mm) of insulation stripped off the end of each wire. Find the wire that corresponds to earth ground
(usuallycolored green) and connect this to the terminal labeled GND. You may determine the ground wire by using
an ohmmeterand testing for continuity with the ground pin on the plug. The other two wires should be connected
tothe terminals marked AC, one wire per terminal. The polarity of the AC power wires with respect to the screw
terminals marked AC on the AC7A/B does not matter.
Figure 2-2: Connector Terminal
INSTALLATION

AC7A/B User’s Guide 9
CONNECTING THE AC7A/B TO YOUR PC
A standard RS-232 serial cable may be used to connect the AC7A/B adapter card to the PC. One end of the
RS-232 cable must have a male 25-pin (DB-25) connector for the AC7A/B. The other end of the cable is for the PC,
and will most likely need either a 9-pin (DB-9) female connector, or a 25-pin (DB-25) female connector, depending
on your computer.
Figure 2-3: Standard Straight-Through 25-Pin to 25-Pin RS-232 Cable
Figure 2-4: Standard Straight-Through 9-Pin to 25-Pin RS-232 Cable
It is also possible to make your own cable for connections between the AC7A/B and an RS-232 device. The only
connections that are absolutely necessary are transmit and receive (RS-232 pins 2 and 3) and signal ground, which
is pin 7 of standard 25-pin connectors. Ground is usually pin 5 on 9-pin RS-232 connectors. (Note: the 9-pin
connector on the AC7A/B adapter card is for RS-485, not RS-232. This sections applies only to the 25-pin [DB-25]
RS-232 connection on the AC7A/B adapter card.)
INSTALLATION

10 AC7A/B User’s Guide
Figure 2-5: 25-Pin to 25-Pin, 3-Wire RS-232 Cable (made by user)
Figure 2-6: 9-Pin to 25-Pin, 3-Wire RS-232 Cable (made by user)
Note: Some serial cables that look like standard straight-through cables are actually null modem cables.
The wiring diagram for a NULL modem cable is shown below:
INSTALLATION

AC7A/B User’s Guide 11
Figure 2-7: 25-Pin to 25-Pin Null Modem Cable Diagram
Figure 2-8: 9-Pin to 25-Pin Null Modem Cable Diagram
To determine whether you have a null-modem or standard cable, perform the following tests:
If you have a cable with 25-pin connectors at both ends, then test the cable for electrical continuity
between pin 2 on one end of the cable and pin 2 on the other end. These two pins are tied together on a standard
25-pin to 25-pin straight-through cable. In a 25-pin to 25-pin null-modem cable, pin 2 of one end is tied to pin 3 of
the other end.
If you have a cable with a 25-pin connector at one end, and a 9-pin on the other end, then test the cable
for electrical continuity between pin 2 on one end of the cable and pin 3 on the other end. These two pins are tied
together on a standard 25-pin to 9-pin straight-through cable. In a 25-pin to 9-pin null-modem cable, pin 2 of one end
is tied to pin 2 of the other end.
INSTALLATION

12 AC7A/B User’s Guide
SETTING THE AC7A/B RS-232 JUMPERS
(FIRST GROUP - NEAR THE 25-PIN RS-232 CONNECTOR)
This group of jumpers is located right next to the DB-25 connector on the AC7A/B. The first 6 pins of the group are
labeled
PIN 2 OUT , PIN 3 IN , and PIN 2 IN , PIN 3 OUT . The rest are labeled by the letters A through H.
This group of jumpers determine which pin on the DB-25 connector is used for transmitting data as well as routing
options for other pins. Detailed information about this is covered later in this manual in “Additonal Technical
Information”.
If you are using a standard straight-through cable to connect the AC7A/B to your PC, then set these jumpers as
shown below:
Figure 2-9: Jumper Settings for Standard Straight-Through RS-232 Cable
If you are using a NULL modem cable to connect the AC7A/B to your PC, you will need different jumper settings.
See Figures 2-7 and 2-8 for more details on null modem cables. The jumper settings for a NULL modem cable
connecting an AC7A/B to a PC are shown on the next page:
INSTALLATION

AC7A/B User’s Guide 13
Figure 2-10: Null Modem Cable Jumper Settings
SETTING THE AC7A/B RS-422/485 JUMPERS
(GROUPS B AND C)
These two jumper groups are located above the green 9-screw-terminal RS-422/485 connector. Group B is on the
left, and group C is on the right. If the AC7A/B is being used in a standard Optomux network in either repeat or
multidrop mode, install the jumpers as shown below.
Figure 2-11: AC7A/B RS-422/485 Jumper Settings for use with Optomux Brain Boards
More details on these jumpers are included in later sections of this manual.
INSTALLATION

14 AC7A/B User’s Guide
CONNECTING THE AC7A/B TO THE OPTOMUX NETWORK
Standard Configuration
For this connection, Opto 22 recommends that you use three pairs of shielded, twisted wire. This comes to a total
of 6 wires in addition to the shield drain wire. All conductors should be stranded #22 or #24 gauge, with a nominal
impedance of 100 ohms and a capacitance of 12.5 pF/ft.
The first pair of twisted wire connects the TO+ and TO- terminals on the AC7A/B to the FH+ and FH- terminals on
the Optomux device (TO+ to FH+ and TO- to FH-). The second pair of twisted wire connects the FO+ and FO- terminals
on the AC7A/B to the TH+ and TH- terminals on the Optomux equipment. The third pair of twisted wire connects
the LOGIC GND terminal on the AC7A/B to the COM terminal of the Optomux device. Finally, the shield of the three
pairs of twisted wire should be tied to earth ground at only one of its two ends.
Figure 2-12: Standard RS-422/485 Wiring from AC7A/B to Optomux Brain Board
For details on connecting multiple Optomux brain boards to the RS-422/485 communication cable, please see the
Optomux B1 and B2 data sheet (form 463).
Alternate Configuration
A slightly less noise-immune connection may be made with a two twisted-pair shielded cable. Instead, use the
shield drain wire of the cable to connect logic ground/common between the two devices. In this case, DO NOT
connect the shield to earth ground.
Figure 2-13: Alternate RS-422/485 Wiring from AC7A/B to Optomux Brain Board
INSTALLATION

AC7A/B User’s Guide 15
APPLY AC POWER
The AC7A/B should now be ready to use with your Optomux network. After all wiring connections are made, and
jumper settings have been checked, it is time to supply AC power to the AC7A/B. The AC7A requires 115 VAC at
50–60 Hz. The AC7B uses 220VAC at 50–60 Hz. Once power has been supplied to the AC7A/B, the LED labeled
PWR ON should become illuminated.
COMMUNICATION LEDS
The communication LEDs are labeled with respect to the RS-422/485 side of the AC7A/B.
The TX (Transmit) LED will flash when the AC7A/B is transmitting data out its RS-422/485 port (i.e., data is entering
the RS-232 port and exiting the RS-422/485 port).
TX = RS-232 —> AC7A/B —> RS-422/485
The RX (Receive) LED will flash when the AC7A/B is receiving data into its RS-485 port (i.e. data is entering
the RS-485 port and exiting the RS-232 port).
RX = RS-232 <— AC7A/B <— RS-422/485
The RTS (Request to Send) LED will turn on when the AC7A/B is requesting to transmit data out its RS-422/485
port. The RTS output tells the other RS-422/485 device that the AC7A/B would like to send data.
RTS = AC7A/B —> RS-422/485
The CTS (Clear to Send) LED will turn on when the AC7A/B is receiving a CTS signal from another RS-422/485
device. The received CTS signal tells the AC7A/B that the other RS-422/485 device is ready to receive data. In other
words, the received CTS signal gives the AC7A/B permission to transmit data out of its RS-422/485 port.
CTS = AC7A/B <— RS-422/485
Note: The RTS and CTS lines are NOT used by Optomux, so the state of the RTS and CTS LEDs is not important
when an AC7A/B is communicating with Optomux I/O devices.
INSTALLATION

16 AC7A/B User’s Guide
INSTALLING THE AC7A/B FOR
USE WITH DEVICES OTHER THAN
OPTO 22’S OPTOMUX I/O
OVERVIEW
The AC7A/B was originally designed specifically to make it easy to connect any device with a standard
RS-232 port to Opto 22’s Optomux I/O in 4 wire RS-422/485 mode. However, the AC7A/B can also be used as a
general purpose, bi-directional RS-232 to RS-422/485 converter.
EQUIPMENT REQUIRED FOR INSTALLATION
• Medium size flat-blade screwdriver
• Wire stripper
• Variety of color-coded wires and cables:
- #22 or #24 gauge twisted-pair cable for communication cables
- #18 gauge for power connections.
MOUNTING THE AC7A/B
The AC7A/B adapter card may be mounted in any position on any flat surface. The AC7A/B is supplied with
3/4” standoffs. All of the standoffs should be secured using #6 mounting hardware to provide maximum
physical strength. Sufficient space should be left around the AC7A/B for serial communication cables and for
power wiring. Figure 3-1 shows the dimensions of the AC7A/B adapter card.
INSTALLATION (cont.)

AC7A/B User’s Guide 17
Figure 3-1: AC7A/B Card Dimensions
CONNECTING AC POWER TO THE AC7A/B
Caution: Make sure that power is OFF while making or removing all connections to the AC7A/B and other
devices. For safety purposes, a plastic insulating cover is provided for the power terminal block and should be
installed after power wiring is completed.
The AC7A/B has a terminal strip with three screw terminals for AC power. The AC power that is supplied to the
AC7A/B should have three wires, two for AC power and one for earth ground (usually colored green). Connect the
wire for earth ground to the center screw terminal which is labeled GND. Connect the other two wires to the
terminals marked AC, one wire per terminal. The polarity of the AC power wires with respect to the AC screw
terminals on the power connector of the AC7A/B does not matter.
If using a standard, 3-conductor power cord with a three-pronged plug, it should be at least #18 gauge wires
or larger. On one end should be the three-pronged plug; the other should have three wires with approximately
1/4” (6mm) of insulation stripped off the end of each wire. Find the wire that corresponds to earth ground (usually
colored green) and connect this to the terminal labeled GND. You may determine the ground wire by using an
ohmmeter and testing for continuity with the ground pin on the plug. The other two wires should be connected to
the terminals marked AC, one wire per terminal. The polarity of the AC power wires with respect to the screw
terminals marked AC on the AC7A/B does not matter.
Figure 3-2: Connector Terminal
INSTALLATION (cont.)

18 AC7A/B User’s Guide
CONNECTING THE AC7A/B TO A PC OR OTHER RS-232 DEVICE
A standard RS-232 serial cable may be used to connect the AC7A/B adapter card to the PC. One end of the RS-232
cable must have a male 25-pin (DB-25) connector for the AC7A/B. The other end of the cable is for the PC, and will
most likely need either a 9-pin (DB-9) female connector, or a 25-pin (DB-25) female connector, depending on your
computer. Figure 3-3 shows the connections between a 25-pin RS-232 serial port and the AC7A/B using a standard
straight-through cable. Figure 3-4 shows the connections between an AC7A/B adapter card and a 9-pin RS-232
serial port using a standard straight-through cable.
Figure 3-3: Standard Straight-Through 25-Pin to 25-Pin RS-232 Cable
Figure 3-4: Standard Straight-Through 9-Pin to 25-Pin RS-232 Cable
It is also possible to make your own cable for connections between the AC7A/B and an RS-232 device. The only
connections that are absolutely necessary are transmit and receive (RS-232 pins 2 and 3) and signal ground, which
is pin 7 of standard 25-pin connectors. Ground is usually pin 5 on 9-pin RS-232 connectors. (Note: the 9-pin
connector on the AC7A/B adapter card is for RS-422/485, not RS-232.)
INSTALLATION (cont.)

AC7A/B User’s Guide 19
This section applies only to the 25-pin [DB25] RS-232 connection on the AC7A/B adapter card.
Figure 3-5: 25-Pin to 25-Pin, 3-Wire RS-232 Cable (made by user)
Figure 3-6: 9-Pin to 25-Pin, 3-Wire RS-232 Cable (made by user)
Note: Some serial cables that look like standard straight through cables are actually null modem cables.
The wiring diagram for a NULL modem cable is shown below:
Figure 3-7: 25-Pin to 25-Pin Null Modem Cable Diagram
INSTALLATION (cont.)