Rockwell Automation 1770-KF2 Data Highway or Highway Plus Interface Module User Manual - Manual (Page 34)

Installation
Chapter 3
3-10
Mechanical Characteristics
The COMPUTER ASYNCHRONOUS connector on a KF2 module is a
male 25-pin D-shell. This connector conforms to the RS-232-C standard
and will accommodate any RS-232-C standard cable (see “Cabling”).
Electrical Characteristics
Selection of either RS-232-C or RS-422-A determines the input and
output levels of the transmit data and receive data circuits on the
asynchronous interface. When RS-232-C standard communication is
selected, all signals on the asynchronous interface are driven and received
by RS-232-C interface circuits which have a maximum drive capability of
50 cable-feet. When RS-422-A standard communication is selected, the
transmit and receive signals only are driven and received by RS-422-A
interface circuits which have a maximum drive capability of
4,000 cable-feet. In RS-422-A mode, all other signals except transmit and
receive still conform to RS-232-C.
The setting of Communication Option Switch 4 of Switch Group SW-1
determines whether the asynchronous port asserts the handshaking signals
or not (see “Asynchronous Link Features”). The handshaking signals are:
RTS, CTS, DSR, DCD, and DTR. When Switch 4 of SW-1 is ON, the
handshaking signals are used. When RS-422-A communications and
handshaking are both selected, handshaking signals are present; but they
conform to RS-232-C standards only.
Cabling
Cabling for the asynchronous port of the KF2 module will vary,
depending on your application and on whether you are using RS-232-C or
RS-422-A communications. The pinouts for the asynchronous connector
are as follows:
Pin
Signal Abbreviation RS-232-C RS-422-A
Protective Ground
Transmitted Data
Received Data
Request to Send
Clear to Send
Data Set Ready
Signal Ground
Data Carrier Detect
Data Terminal Ready
Transmitted Data A
Transmitted Data B
Received Data A
Received Data B
TXD
RXD
RTS
CTS
DSR
GND
DCD
DTR
TDA
TDB
RDA
RDB
1
2
3
4
5
6
7
8
20
1
14
25
16
18