Using The Digital Interface; Modbus Configuration; Modbus Communication - Bühler technologies Peltier TC-MINI Guía Rápida

TC-MINI

5.2 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.

5.3 Modbus Configuration

The settings below are the defaults; the parameters can be ad-
justed 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.

5.4 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 Function code
(A) (FC)
1 byte 1 byte
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
function 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)
Read Holding Registers
Write Multiple Registers
Data types:
Description Number of bytes
Float 4
Int16 2
Uint16 2
Int32 4
Uint32 4
BX440015 ◦ 05/2021
Data CRC
1 ... 252 bytes 2 bytes
FC values
3
16
Number of registers
2
1
1
2
2
6 Maintenance
Always observe the applicable safety- and operating regula-
tions when performing any type of maintenance. Please refer
to the original operator's manual on the included CD or online
at www.buehler-technologies.com for maintenance informa-
tion.
7 Service and Repair
Please refer to the original operator's manual on the included
CD or online at www.buehler-technologies.com for a detailed
description of the unit including information on
troubleshooting and repair.
Bühler Technologies GmbH 9