# Write permissions to an Atlas Copco air compressor



## jakeparsons03 (Oct 5, 2020)

Hello,

I am having an issue communicating with an atlas copco compressor. We are using the Mk5 gateway module to convert modbus RTU to CAN, of which talks to each compressor. We are able to read data from the compressors but we cannot write it. There are 2 issues we have, one of which I believe I know the answer to. 

1 - In our mapping excel sheet AC sent us it lists the LAN command controls as register 2001. I assume that is 42001 as 2001 is only on/off coils. See the pic below for details of what I am talking about. 










2 - I imagine there is some write permission somewhere that I am missing. On Each compressor's elektronikon there is a control mode. We set that to LAN control. I can't find any other permissions on the elektronikon or the gateway module to allow write commands through but I assume there has to be one. 

I have tried to contact AC and their distributors but most of the time they are less than helpful. I talked to one guy who gave me some good information. I believe he confirmed my suspicions on part 1 above but this project was set down for a few months and I want to reaffirm that. 

Does anyone know of something I am missing here in order to be able to write commands to these compressors? I believe the issue lies within the AC gateway or the compressors. 

Below is a (very poorly) sketch of the system operation.


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