Technical FAQs

Ask a Question

How to read energy values from ION meters using modbus register reads?

Issue:
A user would like to read energy values from an ION meter via Modbus register reads. 

Product Line:
ION 7300, 7500, 7600, 7550, 7650, 8300, 8400, 8500, 8600, 8650, series meters

Cause:
There are two register formats that are used to store energy measurements on ION meters. Using a Modbus tester to read 'mod 10' or Int32  type registers will return two types of registers that need to be converted in order to find the Energy decimal value.

Resolution:
There are two register formats that are used to store energy measurements on ION meters The two register formats are Int32-M10k and Int32. The table below shows which meters utilize each of the formats. Review the table and calculation descriptions shown below. 
 

Meters
               Int32-M10K
                     Int32
ION 7300 Series
                               X
                                  X
ION 7500/7600
                               X
                                  X
ION7550/7650
 
                                  X
ION8600
                              X
                                  X
ION8650
                              X
                                  X
ION8800
                              X
                                  X
ION8300/8400/8500
                              X
                                  X


1) 32-bit integer format
To accommodate values that can reach beyond the 16-bit range, the Modbus Slave module provides 32-bit integer format as an output option.

Formula:
Value = registerhigh x 65536 + registerlow
or
Value = registerhigh|registerlow

Example:

 

Calculating the kWh:
230: registerhigh = 18
231: registerlow = 39792
kWh = (18*65536) + 39792
kWh = 1219440

The calculated kWh matches with the real time kWh as viewed in ION Setup. 


2) 32-bit ‘Modulus-10000’ format (MOD10)
The Modulo-10000 (M10K) format breaks a 32-bit value into two 16-bit registers,
according to the following relationship:

Formula:
The 32-bit value can be retrieved by the following calculation:
Value = registerhigh x 10000 + registerlow

Example:


Calculating the kWh:
91: registerhigh = 33
92: registerlow = 716
kWh = (33*10,000) + 716
kWh = 33, 0716

The calculated kWh matches with the real time kWh as viewed in ION Setup. 

Please see the attached PDF "Modbus Protocol and Register Map for ION Devices" for the Modbus register tables and further register format descriptions.
 

Was this helpful?
What can we do to improve the information ?