Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 169)

12–7 Configuration: Host Communications
Publication 2755-833
Transmission Check
Field Type Options
Select
None
LRC
Checksum – LSB
Checksum – MSB
Specifies the type of transmission check that is generated at the end
of a message sent to the host. The default is None, which means no
transmission check is generated.
The decoder can generate three types of transmission checks:
1. LRC (Longitudinal Redundancy Check). A byte developed by
an exclusive OR of all bytes in a message.
2. Checksum–MSB. Sixteen bit sum of all the bytes in a message
with the most significant byte transmitted first.
3. Checksum–LSB. Sixteen bit sum of all the bytes in a message
with the least significant byte transmitted first.
Appendix C provides an example of a transmission check.
Do not use XON/XOFF flow control with transmission check. The
transmission check bytes could be interpreted as an XOFF character.