Changing External Numerical Module value by Modbus using Float data type for PM8000

[TS_Ting]

How do I set up PM8000 so that I can write a floating point by Modbus to an external numerical module? I want to compare this against a measured value to trigger data recording.

[Charles_Murison · Accepted solution]

Hello @TS_Ting ,

If you look at the modbus map for the PM8000. You can see starting at register 52301, The external numeric registers are only 32bit Integer registers. There is no way to make this a float. However this is ION and often possible to do what you want some other way. You could, for example, have the int32 value link to Arithmetic module that takes the int32 value and divide to get a decimal value. for example, the Arithmetic module takes the input and divides by 1000. To get the 6.123 inside the meter's template you would send the module value 6123.

Possible this can get you what you need.

Regards,

Charles

[TS_Ting]

@Charles_Murison Thanks for your response. I have tested what you have suggested and it works.

Just out of curiosity, I understand that the external numerical modules are floating point registers. I have created a custom modbus register to this module and have forced the floating point values using ION Setup and they are coming across properly. Is this custom register read only as I'm unable to write to it?

[Charles_Murison]

Hello @TS_Ting ,

When you use a modbus slave module, you are correct that the register is read only. 

Regards,

Charles