modbus yokogawa PR300 power meter

[Jaime Rodriguez]

I am working on an applicaiton that communicates with a Yokogawa PR300 Power Meter with modbus rtu. I have a rs 232 converter and the labview modbus vis. I am able to communicate with the device because I am getting some values, however i am not sure what i am getting. For example if I use

Function code:  read multiple registers

Starting address: 26 (voltage as stated in the attached manual)

Quantity: 1

I get a value of 39322... What is this value??? Do I need to do something else to the modbus vis? Do I need to do some data conversion on this result???

Please help me in finding this solution...

[Jaime Rodriguez]

Here is the register table

[elite_code_monkey]

Two Options:

(I'd have to read the manual in order to elaborate further, and more accurately)

Anyhow:

1. You either reading an IEEE754 number, or
2. You are reading a number that simply needs to be scaled

...

1. You'd have to read two registers (e.g., starting address: 26 & length: 2).  If this is the case, use the attached VI to get the corresponding floating point value.

2. You'd have to know the (x1, y1) and (x2, y2) pairs in order to compute m and b (of y = mx + b)

Hope this helps

[elite_code_monkey]

starting address: 25, length: 2

feed that into the attached VI (high, and low words - 4-bytes)

[Jaime Rodriguez]

Is it possible for you to send it in Labview 7.1 version.??

[elite_code_monkey]

http://zone.ni.com/devzone/cda/epd/p/id/3469

[Jaime Rodriguez]

If I put the number 39322 in the number field I get the following:

Exponent: 15

Mantissa: 1.2

what exactly is this???? This is converting to binary format....

Could it be with the way the address is defined???? ... SHould it be just register 26 or 40026....

Let me know as soon as you can...

Here is a link to the communications manual for the device..

https://y-link.yokogawa.com/YL009.po?Login_type=2&V_ope_type=Search&Prod_category1_cd=00034&Prod_cat...

[Jaime Rodriguez]

Can you explain a little more what we need to do with that vi????

Thanks a million

[Jaime Rodriguez]

I am able to write to some registers using a software from Yokogawa. This means that the hardware configuration and connections are correct... There is something going on with the Labview modbus part of it...

Just some extra info

[elite_code_monkey]

Unfortunately, I cannot save the VI [which I initially posted] in 7.1 format.

The said VI takes to inputs:  High Word, and Low Word.

High Word would be the value of register 26, and Low World would be the value of register 25 (or vice versa - I can't remember)

The said VI returns a floating point number (which should be the number that you're interested in)

Take a look at the attached image.  It is the block diagram of the said VI.  Reproduce it, and give it a try.

Good Luck.