Rockwell Automation 1770-KF2 Data Highway or Highway Plus Interface Module User Manual - Manual (Page 40)

Installation
Chapter 3
3-16
Figure 3.9
Connection to 1773-KA or 1775-KA Module
25-Pin Female Connector 25-Pin Male Connector
(Cat. No. 1778-CR)
Asynchronous
Port Connector
of 1770-KF2
Module (RS-232-C)
A. Connection Diagram
RS-232-C
Port Connector
of 1773-KA or
1775-KA Module
B. Wiring Diagram
User-Supplied Cable,
Belden 8723, or Equivalent
(50 Feet Maximum)
User-Supplied Connectors
1
3
25
2
7
4
5
6
Port Connector
of 1770-KF2 Module
(RS-232-C)
RS-232-C
25-Pin Female
Connector 25-Pin Male
Connect the Shield
1
7
2
3
4
5
6
8
8
at One End Only
User-Supplied Cable,
(50 Feet Maximum)
Belden 8723, or Equivalent
User-Supplied Connectors
20 20
Port Connector
of 1773-KA or
1775-KA Module
Chassis Ground
RXD
TXD
Signal Ground
RTS
CTS
DSR
DCD
11312
DTR
TDB
Asynchronous
Connector
Answering
The module continually asserts DTR when it is waiting for a call. Under
this condition, the modem will answer a call and assert DSR as soon as it
detects ringing. The module does not monitor the RING indicator in the
RS-232 interface. Once it detects DSR, the module starts a timer (around
10 seconds) and waits for the DCD signal. When the module detects
DCD, communication can start.
If the module does not detect DCD within the timeout, the module turns
DTR off. This causes the modem to hang up and break the connection.
When the hang-up is complete, the modem turns off DSR. This causes
the module to reassert the DTR line and wait for another call. This
feature protects access to the phone if someone calling a wrong number
reaches this station.