Carel pCO2 and pCO3 controllers can be equipped with a Modbus communication card. It is possible to read and write variables through it, prepared in advance in the software in Carel. Some variables can be written, some can only be read (determined by the author of the sw to the Carel controller). The output of the controller supplier should be a table describing the values of all three types, according to which the Modbus variables in the SoftPLC IDE are set.
Carel uses three types of variables: Analog, Integer, and Boolean. An analog is a so-called HVAC integer, ie a signed integer with one decimal place: 201 is interpreted as 20.1.
Analog: read function F03, write F06. All Hi-Lo, Signed.
Addresses start from 2, 3, 4, 5… to perhaps 127. Number of bytes: 2. We give the parameter KP 0.1, thus producing a decimal place.
Integer: read function F03, write F06. All Hi-Lo, Signed.
Addresses start with 130, 131, 132, 133… Number of bytes: 2.
Boolean: read function F01, write F05.
Addresses start with 2, 3, 4, 5… Number of bytes: 1.
Physical parameters of the line: it is necessary to set the BMS address (Modbus slave address), Modbus protocol and speed on the Carel and enable communication with the superior system. Tested on 19200, 8, N, 1, without flow control.
Carel controllers are used, among others, by the company Lennox under the name Climatic 50.