GE Multilin F650, Инструкция по эксплуатации

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B-2 F650 DIGITAL BAY CONTROLLER GEK-106310-AF
B.2 MODBUS F650 APPENDIX B: MODBUS PROTOCOL
B.2 MODBUS F650
B.2.1 Implemented MODBUS functionality
The implemented protocol is standard MODBUS, so any SCADA or PLC can easily communicate with F650 units.
The F650 unit always works as a slave/server, and thus never initiates communication; it is always the master/client
(Enervista 650 Software or PLC, i.e.) that initiates communication.
Only two MODBUS codes are implemented in all firmware versions:
• Read function 3 (03h) and 4 (04h)
• Write function 16 (10h)
Starting from firmware version 7.50 and above, two custom MODBUS functions have also been implemented:
• Read function 66 (42h)
• Write function 67 (43h)
The two new custom function codes allow the master/server to read/write settings of protection functions affected by the
setting groups. If these MODBUS function codes are used, the master/server has access to read/write protection element
settings that belong to any setting group. In contrast, if read function 3 or Write function 4 is used, only protection
elements settings in the
active setting group can be accessed/modified.
B.2.2 Physical layer
MODBUS protocol is independent of hardware. The physical layer may be in different hardware configurations: USB,
RS232, RS485, fiber optic or Ethernet.
F650 units incorporate a front USB or RS232 port, and can mount two rear RS485 or fiber optic ports, and a 1mixture of 10/
100Base TX and 10/100Base FX ports, depending on the specific order code of each F650 unit. The data flow in any of
these configurations is “half-duplex”.
B.2.2.1 Serial layer
The port baud rate and the parity are independent and programmable for each communication port. Any port may be
programmed to baud rates of: 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 115200. Parity may be even, odd, or none.
The master must know the slave address with which it is going to communicate. No unit operates after a master request if
the message address is not its own, unless the address is 0, which is the broadcast address. In this case the relay operates,
but won’t send a reply.
B.2.2.2 B.2.2.2 TCP/IP layer
The rear ethernet or fiber optic ports are used for this connection layer.
The settings for this type of connection are gathered from the Ethernet and MODBUS protocol setpoint menus, where the
IP addresses and TCP port are configured, among other settings.
B.2.3 Data link layer
Communication is performed in strings, with data groups sent asynchronously. The master/client transmits a string to the
slave/server and the slave/server responds with another string (except for the case of broadcast communication). For the
MODBUS serial connection, a timeout or a pause in communication marks the end of a string. The length of this timeout is
equal to 3 characters, thus it varies depending on the baud rate.