The Industrial Raspberry Pi Forum

Hi all,
I connect a gateway module to a RevPi Connect module and watch the data exchange between them via PiBridge's Ethernet channel. In the phase of cyclic data exchange, every approx. 3ms (see picture) a packet is transmitted from the Connect module to the gateway and vise vsa. That means, if I connect an external system (e.g. Profinet) to the RevPi Connect and try to send the process data of the Profinet system to the gateway, if the process data of the Profinet system changes so quickly (< 3ms), then I will lose the data that changed within those 3ms? It's a bug or a trade off? Please correct me!

Thanks for any help!

Yes, you're right and this is kinda intentional.

From our info material:

We have currently set the cycle time between the base modu-
le and a gateway to 5 ms by means of drivers. Though the gate-
way modules could reach cycle times of less than 2 ms, it would
burden the system load of the base module disproportionately.
For the lower the cycle times are set in the driver, the greater
the system load is of the device that has to be expended for
this process

You can check the cycle time on your device with 'piTest -1 -r RevPiIOCycle'.

-Nicolai

Dear Nicolais,
i think the command "piTest -1 -r RevPiIOCycle" should show the cycle time of I/O data on RS-485 channel, not the cycle time of packets on Ethernet. Or i'm wrong?

Dear Songha,
By this way, I want to complete the information given by Nicolai.
RevPiIOCycle actually only looks at the IO modules (RS485 communication). The gateways run asynchronously to this:
Gateway communication runs asynchronously to RS485 communication since release 03/2019. piControl is simply controlled by the gateways. When the gateway sends something, piControl returns a response as quickly as possible.
This means that the cycle time of the gateways depends on the gateway. The corresponding fieldbuses run there without a fixed cycle time according to the best-effort principle.

Best Regards

Ulrich Kouatang Biakoup | Technical Support

Thank you very much for your answers!