Size of Modbus Registers

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pjeannette
Posts: 1
Joined: 09 Mar 2017, 17:18
Answers: 0

Size of Modbus Registers

Post by pjeannette »

Hello

I have configured my revPI3 with Modbus TCP as slave. With Pictory it is only possible to map 32 input and 32 output registers. My customer needs at least to map up to 170 input registers.
Is there any possibility to setup / increase the amount of Modbus registers?

Another question:
Can your Modbus driver be also supported/installed on RevPI core (PI2) version? If so how? Do you have image including the Modbus driver like on the RevPI3?
Thanks.
Regards.
Patrick.
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volker
Posts: 1046
Joined: 09 Nov 2016, 15:41
Answers: 1

Re: Size of Modbus Registers

Post by volker »

There is no difference between the images: You can install the actual Jessie image on Core (CM1) and Core 3 (CM3) systems. So yes, Modbus is available on both systems. But Modbus master with many actions defined could easily get a CM1 based system into full load condition.

There is no easy way to kind of configure more than 32 word and 32 bit inputs/outputs for the Modbus slave.
If you really need this and do not want to use 3rd party software (e.g. there are Modbus libs out there for Python), then the only way would be to go to GitHub, change the Modbus code in our driver and recompile the Kernel. You could additionally also modify the Modbus slave RAP file to get additional registers in PiCtory.

other versions of the virtual Modules with more registers are on the road map but there is no release date for such modules.
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