ION 7350 reading Vll give 6553.6

[CiroF]

Hi

i have an old powerlogic 7350 meter.

concatenate voltage of the system is 11.000 V.

in the modbus map i can find concatenate in register 40015-18 and the readings need to be divided by 10.

The problem is that in a single uint16 you can't store more than 65536 (required 110.000) and infact i have 6553.6 voltage reading.

Am i missing something ? what is wrong ?

Regards

Ciro

[Robert_Lee · Accepted solution]

The ION7350 is a very old ION product but you have a number of available options to allow you to read the voltage.

1. The primary reason you need to divide the value by 10 is the factory default option is to allow 1 decimal point of resolution in Modbus register reads for voltage.  (i.e. If the voltage reading on the 7350 was 120.2 volts, the register would read 1202).  If you don't require this extra digit of resolution and want just the integer portion of voltage you can turn off the scaling via the Modbus Slave module setup register.  You would need to connect to the meter using ION Setup software and go into Advanced ION module view and set the MSR1 Scaling to No from Yes.

2. The second option would be if you do still want to support the extra decimal point of resolution (or maybe more) but can adjust the Modbus Master from reading UINT32 from UINT16 is to modify the MSR1 Format from the default Unsigned 16B to Unsigned 32B (this may require adjust all of the Modbus slave modules as this fundamentally alters the addressing in use).

The easiest option I recommend is to give up the extra digit of resolution.

Also keep in mind that making either adjustment will also affect all voltage/amps/freq readings unless you begin adjusting which readings to into which modules.  You could use the ION Setup Modbus Slave wizard to help in that regard and allow it to perform the necessary changes for you.

[CiroF]

Hi Robert

And Many many many thanks for your answer.

So both solutions, require connection via modbus cable to the device.

I will try as soon as possible.

the plant is in England, and i am in Italy 🙂

but meanwhile does the device have already a modbus data area in which data are stored at 32bit ?

I downloaded the data map but it seems that "extended" data map is available only for other devices 75xx and 76xx not 73xx.

Regards 

Ciro

[Robert_Lee]

No the extended data map may exist for the 73xx but certainly does not include 32 bit versions of existing data.  Unlike most fixed Modbus maps, the ION devices back then allowed users to configure their own map however they wanted.  Also since this product is over 20+ years old 32 bit registers were not supported as well as they are today.