Surefire BMS-350, Инструкция по установке и эксплуатации

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MODBUS INFORMATION
3.0 Basic read/write operation
Basic operation of the BMS-350 with Modbus is as follows:
For reading a register (or registers) the Modbus master sends a holding register read request to the BMS Mod-
bus board using Modbus Function 03 (see “MODBUS APPLICATION PROTOCOL SPECIFICATION
V1.1b”, www.modbus.org for more detailed information about the Modbus protocol and functions). The Mod-
bus board will respond with the contents of the requested registers. There are currently 256 registers defined
(Modbus addresses 40001 thru 40256), but not all are used. Attempts to read registers outside that address
space will return an error according to the Modbus protocol.
While the Modbus board is servicing a read request from the master, it is unable to service simultaneous read
requests from the BMS board for command data. This may result in the BMS board waiting for access and
may result in a blinking LED display on the BMS board. For this reason, it is best for the master to refrain
from reading a large number of registers in a single request, and also to avoid issuing rapid read requests. It is
suggested that read requests be limited to about 10 registers or less at a time, with a maximum read rate of a
few Hz.
For writing a register, the Modbus master sends a holding register write request to the BMS Modbus board
using Modbus Function 6 (write single register) or Modbus Function 16 (write multiple registers). The sup-
plied data will be written to the specified register.
The following table is the register map for the BMS-350. Bits are in MSB first order.
Modbus
address
Register name
Modbus master does
R (Read) or RW
(Read or Write)
Data type Notes
40001 System Mode(R) unsigned int
16
See mode table
40002 Process temperature
(R)
unsigned int
16
Bit 9..0 is 0-511 degrees (RTD)
Bit 9..0 is 0-2400 degrees (Thermocouple)
40003 High temperature limit
(R)
unsigned int
16
Bit 9..0 is 0-511 degrees (RTD)
Bit 9..0 is 0-2400 degrees (Thermocouple)
40004 Low temperature limit
(R)
unsigned int
16
Bit 9..0 is 0-511 degrees (RTD)
Bit 9..0 is 0-2400 degrees (Thermocouple)