PM8000 - Writing to Modbus Registers

[akassabji]

Hello,

I'm trying to write numeric value to Modbus registers on PM8000 (Modbus TCP).

Checking PM8000 Modbus map, found that registers from 52301-52379 (40 registers) are for for External Numeric Value (R/W).

I tried to write to them but I'm getting Exception Code 2 - illegal data address.

FYI, I'm able to read other registers using Modbus TCP (ID:255)

Is there any setting required to change on meter side?

Thanks in advance,

Abdullah 

[Charles_Murison · Accepted solution]

Hello @akassabji ,

This can be done but there are a few steps to confirm

1) What version of firmware are you using? In V3.0.0, you will need to go to the security options module and select Setup registers. The modbus Map Access will need to be set to Read/write. Versions before V3.0.0 also have a setup register for modbus access but the options is a little different.

2) If not using an external numeric module included with the default framework, add the external numeric module

3) When writing to the meter, be sure to write 2 registers, even if 1 register will be zero.

Regards,

Charles

[Charles_Murison]

Hello @akassabji ,

Did any of my suggestions help? If con please consider marking the post as a solution.

Thank you,

Charles

[akassabji]

Hi Charles,

Apologise for the delay. I didn't have a chance yet to check it again.

I'm using PM8000 V2.2.1 I'll try to upgrade to V3.0 and activating reading/writing on Modbus.

Thanks anyway.

Abdullah

[Charles_Murison]

Hello @akassabji ,

Just wanted to follow up to see if you still having trouble.

Regards,

Charles

[ausfrosty1]

Hi Charles,

Is there any way to move an External numeric module value into a Setpoint module? That is I would like to be able to change PM8000 setpoint high or low limits based on a value that is read from another modbus device in the same network.

[Charles_Murison]

Hello @ausfrosty1,
No, the value of the external numeric cannot be linked to the setup register of a setpoint module.

Regards,

Charles

[ausfrosty1]

Hi Charles,

I am trying to trigger a datarecorder by checking if the frequency goes above a variable limit that comes from an external modbus device. With the setpoint module it has the ability to create a trigger that can be fed into the datarecorder module to start the recording but I need to as intimated by my last post be able to vary the setpoint limit.

I am therefor trying to find another way of creating such a trigger. (other than using the setpoint module where the setpoint limit is fixed) Is there any other way of generating a trigger signal based on the comparison of the frequency to an external numeric that you can think of?

I though of trying to use the arithmetic module and passing the frequency and external numeric in and then doinga Frequency > external numrice comparison with an IF statement so that 1 is written when the statement is true and 0 when false. This however will just result in a numeric output of 0 or 1 from that module and no trigger.

Any ideas appreciated.

[sesa56307_bridg]

I think you could probably use a Convert module to complete your idea of using an Arithmetic module.

If you can implement the logic you want using an Arithmetic module (using an IF statement to see if the measured frequency is greater than the limit received over Modbus), then you can link the output of the Arithmetic module (a numeric value of 0 or 1) into a Convert module. The Convert module has pulse outputs for "On Pulse" and "Off Pulse", which will provide a trigger when the value changes state.

I do not know your full application of course, so there may be other factors to consider, but it sounds like an idea that might be helpful. With ION, you can usually find a way to do things like this. Good luck with the framework!

Best regards,

David Tuckey

Firmware Architect

[ausfrosty1]

Hi David,

Thanks for this. It definitely looks like a workable solution. I have implemented it and will get to test on Monday. Will let you know how it goes.

Regards

[jeffhardynetwor]

PM8000: Modbus Register Writing

Hello,

I'm attempting to write a numerical value to the PM8000's Modbus registers (Modbus TCP).

The registers 52301–52379 (40 registers), according to the PM8000 Modbus map, are for External Numeric Value (R/W).

Exception Code 2 - Illegal Data Address is what I get when I try to write to them.

So that you know, I can read other registers with Modbus TCP (ID:255)

Is there a setting that has to be adjusted on the meter side?

I appreciate it,

[Charles_Murison]

Hello @jeffhardynetwor ,

Depending on the meter's firmware version, there is a setup register in the security option module for modbus access permissions. Options could vary but make sure the read/write is selected if available. 

Regards,

Charles

[ausfrosty1]

Hi Jeff,

For your information Charles is referring to the option below in the screen shot.

Also when reading/writing have you tried to use the generic modbus tester found here pictured in the screenshot?

https://ckm-content.se.com/ckmContent/sfc/servlet.shepherd/document/download/0698V00000NrjleQAB

Regards

Robert