Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 13)

Getting Started with Your ASCII Module
Chapter 2
2Ć6
Industrial terminals manufactured before May 1982 allow cross talk
between channels A and B. As a result, data table values could be altered.
Therefore, you should alternate cables between channels for the tutorials
of this manual when using these terminals. When using a series A
industrial terminal, you must alternate cables.
Your industrial terminal has a date code stamped in white on the upper
right corner of the rear label. If your industrial terminal (cat. no.
1770-T3/TA series B) is date coded T 8218 or earlier, or is not date coded,
alternate cables and observe the following warning:
WARNING: When cables are connect to channels A and B at
the same time, cross talk between these channels could cause
the processor to misread inputs and/or misapply outputs, with
possible damage to equipment and/or injury to personnel. For
this reason, do not remove the slide bar that prevents you from
connecting cables to channels A and B at the same time.
If your industrial terminal (cat. no. 1770-T3/TA series B) is date coded T
8219 or later, you can use channels A and B at the same time.
If alternating between channels A and B, connect the 1770-CB cable to
channel B when using the industrial terminal in alphanumeric mode as a
data terminal. Connect the 1772-TC cable to channel A when using the
industrial terminal in PLC-2 (ladder diagram) mode.
As an alternative, use a second industrial terminal in alphanumeric mode
on channel B, or use a Silent 700 data terminal. Connect either to the
1770-CB cable.
Checking ASCII Module Configuration
Your module is configured for RS-232-C operation when shipped from
the factory. If you suspect that its internal configuration (settings of
internal programing plugs) has been altered, you should check module
configuration (refer to section titled Choosing the Mode of
Communication in chapter 3). Do this as follows:
1. Remove covers from the module’s printed circuit board.