Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 297)

Chapter
Call Routines 69–127 13
13 -39
Operational Codes for Half-Duplex Mode:
Operational
code Corresponding mode of operation Special operational code
(same as 0 - 11 except
EOT is suppressed)
0 NHS, Disable DPD, BCC Error Checking 32
1 NHS, Enable DPD, BCC Error Checking 33
2 NHS, Disable DPD, CRC Error Checking 34
3 NHS, Enable DPD, CRC Error Checking 35
4 HDMwoCC, Disable DPD, BCC Error Checking 36
5 HDMwoCC, Enable DPD, BCC Error Checking 37
6 HDMwoCC, Disable DPD, CRC Error Checking 38
7 HDMwoCC, Enable DPD, CRC Error Checking 39
8 HDMwCC, Disable DPD, BCC Error Checking 40
9 HDMwCC, Enable DPD, BCC Error Checking 41
10 HDMwCC, Disable DPD, CRC Error Checking 42
11 HDMwCC, Enable DPD, CRC Error Checking 43
A special range of operational codes (32 - 43) are also accepted.
These codes are identical to codes 0 - 11 except that the end of
transmission (EOT) packets are suppressed. This operation is a deviation
from the standard DF1 protocol and should only be used where
transmissions from a slave module are minimized. When using one of
these selections, the DF1 driver does not respond to ENQuires from a DF1
master unless there is a data packet transmitted.