CHAPTER 4: SETPOINTS DEVICE889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–23CommunicationsThe 8 Series relays have a two-stage communications capability. The base CPU supportsModbus protocol through the Ethernet, USB, serial and WiFi port. In addition, the base CPUalso supports IEC 103, DNP serial, DNP TCP/IP, and TFTP protocol. Once thecommunications module option is added to the base, the base Ethernet port becomesdisabled but the two Ethernet ports on the communications module have enhancedcommunications capabilities such as IEC61850, IEC62439 parallel redundancy protocol(PRP) and IEEE 1588 Precision Time Protocol (PTP). The communications CPU also supportsModbus TCP, IEC 104, DNP TCP, TFTP, SFTP, and SNTP protocol.Modbus Protocol All Ethernet ports and serial communication ports support the Modbus protocol. The onlyexception is if the serial port has been configured for DNP or IEC 60870-5-103 operation(see descriptions below). This allows the EnerVista 8 Series Setup software (which is aModbus master application) to communicate to the 889.The 889 implements a subset of the Modicon Modbus RTU serial communication standard.The Modbus protocol is hardware-independent. That is, the physical layer can be any of avariety of standard hardware configurations. This includes USB, RS485, fiber optics, etc.Modbus is a single master / multiple slave type of protocol suitable for a multi-dropconfiguration.The 889 is always a Modbus slave with a valid slave address range 1 to 254.DATA FRAME FORMAT AND DATA RATEOne data frame of an asynchronous transmission to or from an 889 typically consists of 1start bit, 8 data bits, and 1 stop bit. This produces a 10-bit data frame. This is important fortransmission through modems at high bit rates. Modbus protocol can be implemented atany standard communication speed. The 889 supports operation at 9600, 19200, 38400,57600, and 115200 bps baud rate. The USB interface supports ModBus TCP/IP.FUNCTION CODE SUPPORTEDThe following functions are supported by the 889:• FUNCTION CODE 03H - Read Setpoints• FUNCTION CODE 04H - Read Actual Values• FUNCTION CODE 05H - Execute Operation• FUNCTION CODE 06H - Store Single Setpoint• FUNCTION CODE 07H - Read Device Status• FUNCTION CODE 08H - Loopback Test• FUNCTION CODE 10H - Store Multiple Setpoints• FUNCTION CODE 42H - Group Settings Read• FUNCTION CODE 43H - Group Settings WriteWhen a ModBus master such as the EnerVista 8 Series Setup software communicates tothe 889 over Ethernet, the 889 slave address, TCP port number and the 889 IP address forthe associated port must be configured and are also configured within the Master for thisdevice. The default ModBus TCP port number is 502.The following ModBus parameters are configurable:Path: Setpoints > Device > Communications > Modbus Protocol
