Saia with PCD.F520

Hi Experts,

We have a Saia PCD2 with a PCD2.F520 (expansion card with RS232 and RS485). We want to connect both a HMI and a SCADA to this card. Is it possible to connect the SCADA to the PCD2.F520's RS232-port and the HMI to the PCD2.F520's RS485-port or you should only use one of these ports at the same time?

Thanks for your thoughts!

//Supporter

Yes, you can use both ports simultaniously as S-Bus connections (included in operating system) or use modbus ,comli or other protocols if you include the proper library in your aplication.

You may also use port0 (PGU port in front) for HMI at the same time,if you dont overload the cpu.
Depending on how old your cpu is Fw/HW you have different choises.

Regards
Bardes

Hej Bardes,


Thanks for the information. A few questions, how do we know if/when we "overload" the CPU? What will happen if we overload the CPU, will it not respond to SBUS-messages?

Thanks!

//Supporter

As already mentioned, you can use both channels (.F520: Ch2=RS232 and ch3=RS485/422) at the same time. But there is a limitation, there are some combinations of baudrates on the DUART (ch0+ch1 or ch2+ch3) that you can't use. 38400+38400 or 38400+19200 won't work.
If you are going to use the SBUS-protocol be also aware that you can only define (HW config and download) one channel as SBUS PGU. The other channel(s) have to be define through user program with IL or FUPLA.
There are 3 versions of the SBUS protocol and I think Beijer only support 2 of them? The Datamode was the latest version, but if the PLC-battery is a button-cell, then it is supported for sure.
Be also aware there is a jumper on the F520-card for RS485 line termination. Closed on end-stations.
BTW, the errorlamp should not lit, should it, then there is an indication that "something is wlong..."
Regards

Normally this will not be a problem, because the pcd has priority on communication.
You may have a problem if you select the highest speed,the most intens communication, demanding, time critical protocols and at the same time have a high cpu load in your plc programs.
This means that the pcd will need more time to serve ports and the program cycle time will increase.
Normally there is no problem with a scada and 1 or more HMI because HMI often need a limited amount of data. It often only read the data shown on a the current page and some alarms.

In a scada system you also often read the data from the plc with different time intervals, because all information is not interesting all the time, and/or the plc send data when status is changeing.

Regards
Bardes