Modbus Communication - Bühler technologies RC 1.1 Notice De Montage

RC 1.1, RC 1.2+
5.3 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.
5.4 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.

5.5 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:
BX450028 ◦ 09/2021
Data CRC
1 ... 252 bytes 2 bytes
FC values
3
16
Description Number of bytes
Float 4
Int16 2
Uint16 2
Int32 4
Uint32 4
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.
7.1 Troubleshooting
Problem/Mal- Possible cause
function
Condensate • Condensate trap
inside the gas full
output
• Valve inside the
automatic con-
densate drain
may be stuck
• Cooler overload
Reduced gas • Gas circuit
flow rate clogged
• Condensate out-
put iced over
Excess tem- • Operating point
perature not yet reached
• Cooling output
too low despite
the cooler run-
ning
• Flow rate/dew
point/gas tem-
perature too
high
• Built-in fan
stopped
Temperature • Controller fail-
low ure
No cooling • Compressor
doesn't start up
Number of registers
2
1
1
2
2
Action
• Empty condensate
trap
• Flush in both direc-
tions
• Maintain limits
• Remove and clean
heat exchanger
• if necessary, replace
filter element
• Send in unit
• Wait (max. 20 min)
• Ensure the vents are
not covered (heat
buildup)
• Maintain limits/in-
stall pre-separator
• Check and replace if
necessary
• Send in cooler
• Compressor PTC not
cooled down suffi-
ciently. Wait 5
minutes and try
again.
Bühler Technologies GmbH 17