Modbus POE ETH Relay dry interface data communication references
Product datasheet - 8-ch Ethernet Relay Module, Modbus RTU/Modbus TCP Protocol, PoE port Communication, With Various Isolation And Protection Circuits - https://www.waveshare.com/modbus-poe-eth-relay.htm Documentation Modbus POE ETH Relay - https://www.waveshare.com/wiki/Modbus_POE_ETH_Relay help me about read data by using modbus c# - https://www.plctalk.net/threads/help-me-about-read-data-by-using-modbus-c.95485/ Advantech User Manual PCI-1761 - 8-ch Relay & 8-ch Isolated Digital Input PCI Card - https://advdownload.advantech.com/productfile/Downloadfile1/1-11P6657/PCI-1761.pdf +++ Check modbus using Wireshark