GE VersaMax PLC, User Manual

Page: 272 / 318

13.6.5 Station Manager Lockout under Heavy Load
Sustained heavy EGD and/or SRTP Server load can utilize all processing resources within
the Ethernet interface, effectively locking out the Station Manager function. The Station
Manager appears inoperative under either local or remote operation. The Ethernet
interface always gives higher priority to data communication functions than to the Station
Manager. When the processing load is reduced, the Station Manager becomes operative
once again.
This condition is not reported to the PLC Fault Table or Ethernet exception log.
13.6.6 PING Restrictions
To conserve network data buffer resources, the CPUE05 process only one ICMP control
message at a time. An ICMP Echo (ping) request that arrives while the CPUE05 is
processing another ICMP control message is discarded. When multiple remote hosts
attempt to ping the CPUE05 at the same time, some individual ping requests may be
ignored depending upon the timing of the ping requests on the network.
The CPUE05 may initiate ping requests to another host on the network via the ping
Station Manager command. The ping request sequence is restricted to one remote host at
a time.
Discarded ping requests are not reported to the PLC Fault Table or Ethernet exception
log.
13.6.7 SRTP Connection Timeout
When a remote SRTP client is abruptly disconnected from a CPUE05 (for example, by
disconnecting the Ethernet cable), the underlying TCP connection attempts to re-establish
communication. The SRTP connection in the CPUE05 remains open for approximately 5
minutes while TCP attempt to reconnect; during this interval, the SRTP connection is
unavailable. If all the SRTP connections in the CPUE05 are in use or otherwise
unavailable, a new SRTP client connection must wait until the TCP reconnect time
expires on an existing connection.
The SRTP connection timeout is normal expected behavior, and is consistent with other
GE PLC products.
272 GFK-1503E VersaMax PLC User Manual
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