Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 14)

Chapter 1
Introducing the Control Coprocessor
1-4
Table 1.C describes the hardware elements for the optional serial
expander module.
Table 1.C
Serial Expander Module Hardware Elements
Hardware
Element
Description
Keyswitch
This is a 2Ćposition, springĆloaded keyswitch
The RESET position is used to reinitialize the control coprocessor without cycling power
ASCII Display
The 4Ćcharacter alphanumeric display shows information on the state of the control
coprocessor, as provided by user programs
LEDs The two status indicators provide information on the COMM2 and COMM3 ports
COMM2 Port
and
COMM3 Port
These are 25Ćpin, optically isolated, serial communication ports that support
communication defined by EIA RSĆ232C, Ć423, and Ć485 standards
You can also use the port with most RSĆ422A equipment as long as:
• termination resistors are not used
• the distance and transmission rate are reduced to 200 ft at 19.2 kbps
Use these communication ports to connect peripheral devices such as:
• terminals
• personal computers
• barĆcode readers
• weigh scales
• printers
Fault Relay
The relay contact switches on a detected mainĆmodule hardware fault; the relay will
handle 500 mA at 30 Vac/dc (resistive)
The control coprocessor communicates with a programmable controller
through a direct connection to the programmable controller—direct-
connect mode—or via the 1771 I/O chassis backplane—standalone mode.
When you use the serial expander module in either mode, place it
immediately adjacent to the main module under the same locking tab.
DirectĆConnect Mode
In direct-connect mode, either the control coprocessor or the PLC-5
R
programmable controller initiates communications. The control
coprocessor can read from and write to the PLC-5 programmable
controller data table asynchronously to the ladder-program scan.
You can directly connect the control coprocessor to a PLC-5
programmable controller that has the coprocessor expansion port—
e.g., a PLC-5/11
t, PLC-5/20t, PLC-5/20Et, PLC-5/30t, PLC-5/40t
(series B, revision B or later), PLC-5/40E
t, PLC-5/40Lt, PLC-5/60t
(series B, revision B or later), PLC-5/60L
t, PLC-5/80t, and
PLC-5/80E
t programmable controller.
19397
Modes of Communication
with a PLC Programmable
Controller
19398
A control coprocessor and serial
expander in directĆconnect
communication with a PLCĆ5
programmable controller