Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 299)

Chapter
Call Routines 69–127 13
13 -41
Operational Codes for Full-Duplex Mode:
Legal values for the operational code are 16 to 31 for full-duplex mode:
Operational code Corresponding mode of operation
16 NHS, ER, Disable DPD, BCC Error Checking
17 NHS, ER, Enable DPD, BCC Error Checking
18 NHS, ER, Disable DPD, CRC Error Checking
19 NHS, ER, Enable DPD, CRC Error Checking
20 NHS, ADER, Disable DPD, BCC Error Checking
21 NHS, ADER, Enable DPD, BCC Error Checking
22 NHS, ADER, Disable DPD, CRC Error Checking
23 NHS, ADER, Enable DPD, CRC Error Checking
24 FDM, ER, Disable DPD, BCC Error Checking
25 FDM, ER, Enable DPD, BCC Error Checking
26 FDM, ER, Disable DPD, CRC Error Checking
27 FDM, ER, Enable DPD, CRC Error Checking
28 FDM, ADER, Disable DPD, BCC Error Checking
29 FDM, ADER, Enable DPD, BCC Error Checking
30 FDM, ADER, Disable DPD, CRC Error Checking
31 FDM, ADER, Enable DPD, CRC Error Checking
Important: Select other port parameters, such as communication rate,
number of stop bits, and parity with the MODE command (page 11 -20)
before you enable DF1. The modem handshaking selection made here
overrides the handshaking parameter of the MODE command until DF1 is
disabled.