Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 46)

Choosing Module Features
Chapter 3
3Ć4
AĆB Long Line
Use A-B Long Line for communicating up to 5000 cable feet between an
industrial terminal, serving as an ASCII device, and the ASCII module.
Refer to Table 2.D for a detailed listing of A-B Long Line pin functions.
Table 2.D
AĆB Long Line Connector Pin Functions
Pin No. Signal Name Source Function
2 Transmitted Data AĆB Long Line Device Data Transfer to 1771ĆDA
7 Transmitted Data Return Return for transmitted data
11 Received Data 1771ĆDA Data transfer to AĆB Long Line Device
25 Received Data Return Return for received data
Selecting the Communication Mode
The communication mode that you choose depends on the cable distance
from your ASCII device to your ASCII module, and on characteristics of
your ASCII device (Table 2.E).
Table 2.E
Mode of Communication
If Distance is
Less Than And Your ASCII Device is a
Then Choose this
Transmission Mode
50 feet Data Terminal Equipment (DTE) and conforms
to RSĆ232ĆC
without control lines
with control lines
Data Set (modem) and conforms to RSĆ232ĆC
without control lines
with control lines
RSĆ232ĆC (Figure 2.1)
4Ćwire cable
8Ćwire cable
RSĆ232ĆC (Figure 2.2)
4Ćwire cable
8Ćwire cable
500 feet DTE and provides a 20mA current source for
the transmit line, only
DTE and requires a 20mA external current
source for its transmit line
DTE and provides 20mA current sources for
transmit and receive lines
Current Loop (Figure 2.3)
The module powers its own transmit line.
Current Loop (Figure 2.4)
You add the power supply for the DTE.
Current Loop (Figure 2.5)
The module operates in passive transmit.
5000 feet AĆB industrial terminal or contains a line driver
receiver for AĆB long line operation.
AĆB Long Line (Figure 2.6)