Do we know the cycle rate to command other controllers?
How fast can a PV450/PV750 poll other devices?

Depends on what this means. I believe the rate they’re looking for is the shortest period between samples of another controller – I would suggest no shorter period than 100ms currently on the PV750 or PV450 (that will improve in the future). However, you can set recurring timer rates as fast as 10ms – we just haven’t tested the accuracy to that level yet.

Some variability in the polling rate would also be influenced by the port they’re using. If they’re polling via CAN or RS485, bus load can be a factor among other things.

In the current PV750 and PV450, the loop time base with timers in the CCM is set at 50ms. Even though the time allowed for input in the configuration tool can be set down to 10ms and anything greater, the result will be rounded to a 50ms timer boundary on the running system. Therefore it is recommended at this time when timers are used in state machines to keep all the time values on 50ms boundaries for the best deterministic behavior.