UNIFLAIR BREC1812 - Not Communicating over ModBus RTU

[BillP]

Dear All,

We have installed BREC1812 UNIFLAIR Chillers in one of our project, we have installed ACAC76123 Serial Cards to communicate over RTU for our BMS System, however we are not able to communicate over the RTU, we have already configured ModBus Parameters for both Chillers.

Can someone please help us in identifying this issue.

Regards,

Waleed

[BillP · Accepted solution]

Hello Waleed.

There are only a couple parameters on the unit to set for the Modbus.

SETTING TRANSMISSION PARAMETERS FOR SUPERVISION
The following screen allows the basic parameters to be set (first three lines) for
switching via supervision, i.e.
1. serial address of the unit connected to the serial supervision network
(must match serial address set in supervision programme);
2. data transfer rate (Ser. speed): 1200, 2400, 4800, 9600 and 19200 for
RS-485. (keep this at 9600 or 19200.
3. protocol type (standard or Modbus). (would be modbus in this case)

Some other things to try is to swap the wires on the card. Check is a resistor is needed at the end of the modbus chain. Try changing the parity on the Master to see if the values start reading. If these do not work, please call your local tech support to further troubleshoot the machines.

Thank you