GE PACSystems RX7i, User Manual

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Chapter 12. Diagnostics
GFK-2224Q January 2017 239
Accelerated EGD Consumption Can Interfere with EGD Production
Consumed EGD exchanges received from the network normally receive accelerated processing for increased
overall EGD performance. This accelerated processing can preempt EGD production activity, possibly delaying
transmission of produced exchanges to the network. Such delay varies with network loading and the volume of
consumed exchanges. In applications requiring minimal produced exchange timing variability, the consumed
exchange acceleration may be disabled via the “gc_accel” AUP parameter. (See Appendix A for details of the
“gc_accel” parameter.) Under extreme network load, accelerated processing of the incoming EGD samples
may consume so much processing time that the watchdog timer for the network interface expires and the
network interface is reset.
Channels Operation Depends Upon PLC Input Scanning
Communication channels operation always includes updating the Channel Status Bits (located within the
Ethernet Status data) into PLC memory, which occurs when the PLC scans inputs from the Ethernet module. At
least one PLC input scan must occur for each data transfer on a channel, so the channel can run no faster than
the PLC scans the Ethernet Status data. When the Ethernet interface is configured to use an I/O Scan Set than
runs more slowly than the PLC sweep, each channel must wait until the next time that its scan set runs to
transfer its Channel Status bits. This can reduce channels performance.
If the Ethernet interface is configured to use an inactive I/O Scan Set, the Channels Status bits will not be
transferred and channel operations will not complete.