TC-MIDI (+)
5.5 Using the Digital Interface
The digital interface on this device is a Modbus RTU protocol, which physically communicates via RS485 (2-wire). The cooler
therefore takes on the role of the slave in communication.
The Modbus interface enables direct access to process and diagnostic data and parameters during operation.
5.6 Modbus Configuration
The settings below are the defaults; the parameters can be adjusted if the interface is enabled.
1 start bit
8 data bits
1 parity bits (configurable)
1 stop bit (*)
Baudrate: 19200 bps (configurable)
Device ID: 10 (configurable)
(*) The length of a Modbus frame is always 11 bit, configuring the interface at 0 data bits automatically changes the number of
stop bits to 2.
5.7 Modbus Communication
Communication via Modbus RTU is always imitated by the master (request). The slave (typically) responds to the request with a
response. A Modbus RTU frame for a request/response always has the following structure:
Address field (A)
Function code (FC)
Data
CRC
1 byte
1 byte
1 … 252 bytes
2 bytes
Register addresses and data are transferred in Big Endian format.
Every register stands for a 16 bit value, with the information represented in various data types. The data type and required func-
tion code are assigned to the respective registers in the following tables.
To read/write data types with sizes larger than an individual register, multiple registers must be addressed.
Supported function codes:
Function code (FC)
FC values
Read Holding Registers
3
Write Multiple Registers
16
Data types:
Description
Number of bytes
Number of registers
Float
4
2
Int16
2
1
Uint16
2
1
Int32
4
2
Uint32
4
2
26
Bühler Technologies GmbH
BE440016 ◦ 07/2022
Содержание ModbusRTU TC-MIDI
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