ION Meter Setpoint Module – Setup Register Read/Write via Modbus

[Stuart_Cheng]

Hi All,

I’m using the setpoint module on an ION meter to configure some alarms. I’m wondering if the setpoint high/low limits are available for read and write via Modbus?

I tried setting up a Modbus tag, but it seems I can only select the output registers and not the setup registers. Has anyone encountered this or know a workaround? Thank you!

[Mehran_Mehrnia · Accepted solution]

Hi @Stuart_Cheng 

Given that using the Modbus Slave Module makes ION register values available to a Modbus master device, or that additional Modbus registers such as Numeric Registers starting at 56001–59999, are assigned for writing values to some ION module registers over Modbus:

it’s important to note that, as mentioned in another forum discussion on 'Writing to Modbus Registers' the setup register values of a module cannot be written over Modbus and cannot be linked to the Modbus Slave Module for reading or to an External Numeric module for writing.

Please also note that, the meter's Security Options Module (SOP1) has its Modbus Map Access setting changed from the default of "No" to "Yes" to permit Modbus writes to your custom registers.

Using native ION application software such ION Setup, PME apps, it's possible to read/write the Setup registers of ION Modules.

Best Regards,

-Mehran

L3 Expert Advanced metering

[Charles_Murison]

Hello @Stuart_Cheng ,

To link a setup register in ION Setup, before you click the link button hold down the Ctrl key then click the link button. This will tell ION Setup to use Setup registers rather than output registers. You can use this to link Setpoint module setup register to Modbus Slave module input to be able to read the High/Low limits. 

Writing to a setup register is a different story. Registers linked to Modbus slave modules cannot be written to. Only if the setup register is linking to the default Modbus mapping can a write be possible.

External numeric modules can be written to via modbus if permissions are set. You could change the framework to do calculations based on External numeric value and the measurement in question. Then link the output of the calculation to the setpoint module to make the alarm. 

Regards,

Charles

[Charles_Murison · Accepted solution]

Hello @Stuart_Cheng ,

I tried to link a setpoint module's Setup registers directly to a modbus slave input was unable to make the link. However I was able to link to an Arithmetic module. You could feed the output of the Arithmetic module to a modbus slave module to get access to the value via Modbus.

Regards,

Charles 

[Stuart_Cheng]

Hi @Charles_Murison @Mehran_Mehrnia,

Thanks for sharing all the information. I also ran some tests and would like to confirm a few points:

1. Regardless of the ION module used, setup registers cannot be linked to a Modbus slave module for reading.

2. When writing values to the ION meter via Modbus, the available registers are limited to those listed in the Modbus Map file—specifically ranges 52001–53000, 54001–56000, and 56001–59999. These registers are predefined and cannot be modified.

   
3. To read or write the limit of a setpoint alarm, an alternative approach is to write the limit value to an external module, link it to an Arithmetic module for logic or calculations, and then use Setpoint module to generate alarm.
   
   Appreciate any feedback!

[Charles_Murison]

Hello @Stuart_Cheng 

1. That is my understanding however I have not tested with every possible module. At least with ION Setup.

2. Refer to the detailed modbus map section, look for registers with R/W.

Regards,

Charles

[Stuart_Cheng]

Thank you @Charles_Murison!