2/14/2016 1:32 PM | |
Posts: 7 Rating: (0) |
Hi, Am using S7 400H with CP 443-1 for modbus TCP/IP communication. I have enclosed the program backup. At present we have two modbus servers (MOXA serial to TCP gateways) which connected to redundant CPs (as client). There are several modbus slaves connected to one gateway and the gateway TCP port connected to CPs. In user program we are trying to poll the serial slave data via TCP protocol, one by one based on done or error bit of the modbus block. In some case the modbus blocks stops and it is necessary to initiate the ENQ bit, hence we have added on-delay timer on OB1 to set the ENQ bit when there is no updation on Done or Error bits. We are facing the following problems, 1) The polling cycle for all devices getting delayed because the switching of polling is not happening automatically, it is waiting for the On-delay timer to set the ENQ bit to "1" every-time. After the successful polling it is not automatically switching to other devices. When i manually set the ENQ bit in VAT table then the modbus polling are faster and automatically switching to other devices for sometimes only, when that automatic switching stops then it is completely relying on the On-delay timer to set the ENQ bit. I couldn't get where the problem is. 2) We have 2 modbus servers hence 2 modbus "REDCL" blocks were used. We have tried for simultaneous polling of both servers, the block shows "Busy". Will S7 CPs supports for multiple TCP servers simultaneously? 3)Modbus redundancy is not working. Whenever the primary CPU/CP fails the secondary CP is not taking over. 4) Also we need to identify the modbus node healthiness status to display on SCADA. During COM failure the modbus data is showing the last values and it needs to show zero. Kindly advise to resolve. Thanks,
AttachmentAJMN_CAR_PMS_110216.zip (359 Downloads) |
Follow us on