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About These Examples
ASCII Module with ControlLogix System
Application Examples
For these application examples, the POINT I/O ASCII modules are used
directly with a CompactLogix 5370 controller over an Ethernet network. The
ASCII modules act as a normal slave to the master scanner. The data that is
sent to and from the scanner contains the ASCII data and some specialty bytes.
Serial Port Connector
The ASCII devices are connected to the ASCII modules via a:
•
3-wire communications cable for the RS-232 network.
•
2-wire communications cable for the RS-485 network.
•
4-wire communications cable for the RS-422 network.
.
Table 20 - Module Terminations
Terminal
RS-232
(1)
0
Tx
(2)
1
Rx
2
NC
3
NC
4
NC
5
NC
6
NC
7
SG
(1) S+ and Tx+ are transmit from the module
(2) S- and Rx- are receive into the module
Send Data Through the ASCII Modules
To send data from the master scanner through the ASCII modules, the desired
data should be written into the data area, starting at byte 5 after the header.
Next, the number of bytes to be transmitted should be put into byte 4 of the
header. Lastly, the Transmit Record Number byte 2 must be changed from its
previous value to trigger the transmission (for instance, by incrementing the
ID value by 1 each time a message is to be sent).
Rockwell Automation Publication 1734-UM009C-EN-P - August 2022
RS-485
RS-422
(1)
(1)
S+
Tx+
(1)
NC
Rx+
(2)
(2)
S-
Tx-
(2)
NC
Rx-
NC
NC
NC
NC
CG
CG
SG
SC
A
Appendix
37
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