GE VersaMax PLC User Manual page 235

Major Error
Code
Serial I/O / SNP / RTU Protocols
For public disclosure
Modem responded with RING, indicating that the modem is
being called by another modem. Modem is unable to
10 (0Ah)
complete the requested command. Retry the modem
command later.
Unknown response received from the modem. Modem
11 (0Bh) unable to complete the request. Check the modem command
string and modem. Response should be CONNECT or OK.
COMMREQ timeout. The COMMREQ did not complete within
50 (32h)
a 20-second time limit.
Description
GFK-1503E User Manual 235