Chapter 6. Serial I/O, SNP & RTU Protocols
GFK-2222AD
April 2018
203
6.1.4
Invalid Port Configuration Combinations
The Machine Edition programming software safeguards against the download of some hardware
configurations that would prevent the programmer from communicating serially with the CPU. In a
system that does not have an embedded Ethernet module, if a rack-based Ethernet is not present, a
serial connection is required for programmer communications.
For CPE302/CPE305/CPE310 CPUs, which have an embedded Ethernet port that, when configured, is
available for programmer communications, the safeguards on serial port configurations are still
enforced.
For CPE400, which only supports the Serial I/O protocol, the only valid operation, using this COMMREQ,
is to enter Serial I/O as the Protocol Selector (refer to Section 6.1.5).
