TRP-C28 provides with 4 optical isolated digital input channels and 4 power relays output. All channel features screw terminals for convenient connection of field signals as well as LED?s to indicate channel status.??Input channels are equipped with 3750Vms DC isolation, and surge protection on RS-485 data lines that protect the module and divece against high power voltage input and ground potential differences. For easy user access, TRP-C28 can enter configuration mode and self-test mode with outer dip-switch. TRP-C28 support both ASCII and Modbus protocol, with?a full set of command, dual watch-dog, and auto reset function the module?can be bi-directionally remote controlled by PC in ASCII or Modbus RTU protocol.