Modbus Communications problems between Carel c3-05 PCO with ABB AC800f

Dear all,

Hi, i would like to start by saying i am new and not a refrigeration engineer, so please bear with me if i sound a bit like a newbie.
Ok! I have a ABB Freelance AC800f controller with a serial Card for Modbus RTU (rs485) Communication and a Carel C3-05 PCO Controller with PCO1004850 Serial Card(rs485) for a DENCO HVAC Unit.

I am using a
- two-wire bus plus shield
- impedance of 120ohms
- only device connected
- length not more than 15ft (AWG 22 twisted and shielded)
- baud rate and address confirmed

no communication between the two controllers. I have done everything over and over again, but i am unable to find the problem. I would really appreciate some assistance in this matter. As there are any known issues between these two particular controllers which are not publicised.

Thank you in advance to those who do reply.

Are you seeing the unit at your head end?

I am a little confused on what you are trying to do? remote monitor or use modbus to control duty/standby.

Quote:

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Originally Posted by Denco Technical

Are you seeing the unit at your head end?

I am a little confused on what you are trying to do? remote monitor or use modbus to control duty/standby.

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Well i am trying to remotely monitor the units, ofcourse it does give me the option to program a duty/standby scheme which i will go for after i have completed the first phase, i will not using the PCO's own method of doing it.

Okay there is a few setting I would like you to check.

First of all are you happy the card is pushed in correctly and located in the serial card slot.

When this is connected you need to configure the controller:

Level three

BMS communication:

Protocol > Modbus (press right key to enter)

Address > Set to your desired network address (must be different on all units) press right key to enter

BMS Comms Baud rate > Set at 9600 ( you may need to play about depending on how fast the network is) press right key to enter

BMS> Either on for total remote control or off for monitoring only press right key to enter

If you set all these there should be no reason why you cannot see it on the network.

Below is the link to the C3-05 manual which has the level password for 1, 2 and 3.

http://www.mediafire.com/file/ylh4c7s2s8fwc52/C3-05%20Controls%20O%26M%20Version%203.1.pdf


Below is the Modbus scans for your info:

http://www.mediafire.com/file/qdcg6qycaxrbd1z/Denco%20Supervisory%20Variable%20List1%20%20V1%2010%20with%20Modscan%20ID%27s.xls

The duty/standby will be controlled by the machine.

Please see page 24 and 25 of the C3-05 manual.