Prosoft Gateway

I used three Prosoft gateway converters to convert the communication protocol from Modbus plus to Modbus TCP to Profinet between two PLCs.
Now, the signal is sent and received well from PLC to PLC by three gateways.

What I am worried is that the request and response time among the device may delay and have communication error.

Do anyone have used three gateways between two PLC ? Are there no communcation error?
The better one is that three gateways are same brand, Prosoft.

Hello hcjs123:
I wish I could provide you a useful answer, but your question is a little bit vague; nonetheless I give it a try. Since you do not mention the brand of your PLCs and the communication boards available on them, I have to take your word that the only possible way do achieve the goal of communicating the two PLCs is through three gateways. If this is the case, and if you managed to communicate the PLCs, well, of course there is a delay since there are many links in the chain. The important thing is what is the worst delay that your system would tolerate and what performance did you actually achieve. If these values are too close, then of course you may have problems. I have done PLC interfacing applications but for data monitoring, not for control of IO on the other side. The control part is done separately by each PLC through its native IO system and by means of a two gateways (one for Simatic S7/MELSEC TCP, the other MELSEC TCP/TC NET). In that application some values from one PLC are sent to the other periodically. I advice that you program some kind of heart bit logic in case it is important to detect on one PLC system whether the other has stopped either by user fault, or hardware fault or by setting the PLC to STOP or programming mode.

Hello Alfred


I am not using three gateway of Modbus Plus, Modbus TCP, Profinet.
Three gateways are between Schneider PLC and S7 PLC.
I think that I can add Error code or heart bit in Step 7 as you advised.

If the communication has problem and timeout, the error code can be displayed in Step7. Then I can easily recognize it.

I appreciate your advice.

This is the case for communication error, such as if the LAN cable is disconnected from the other PLC. I am referring to the case in which the other application goes to fault due to a problem in the logic, or if the other PLC is put in stop or programming mode. In this case there is no communication timeout and so the S7 has no way to detect that the other PLC is not running. This is why I advice the heartbeat. If the S7 notices that the heartbeat value does not change AND there is normal communication it can only mean that for some reason the other PLC application is not running.

Thank you for advice. I will add heart bit to S7 PLC.
Thank you.