RS485 Modbus & IME Power Meter

JonAW

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Sep 2013
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Hi Guys,

I hope some of you more knowledgeable people can help me?

I'm currently configuring an AB ML1400 to talk to a IME Power Meter over Modbus RTU RS485. This is my first time using the ML1400 with Modbus and it seems reasonably straight forward. After prep'ing myself with reading the manuals and reading modbus threads on this forum when it came to setting up the comms I got a reply from the power meter straight away after having to swap the A & B wires around. The reply time is approx 50ms.

I'm looking to read input registers so have setup the commands as follows to test the data retrieval before going further. I'm looking to read the Phase 1 Voltage in address 0x301 as per the Power meter modbus manual (See attached):

Command: 04 Read input registers
Data Table Address N12:0
Size In Elements: 4
MSg Timeout:4
MB Data Address: 1
Slave Node: 1
modbus address: 30001

My issue is the reply I'm getting is Error Code (hex) 81 - Modbus Exception Code 01 returned: Illegal Function.

Has anyone got any ideas why the meter is not reading my request properly?

Regards

Jonny
 
Hi Guys,

I hope some of you more knowledgeable people can help me?

I'm currently configuring an AB ML1400 to talk to a IME Power Meter over Modbus RTU RS485. This is my first time using the ML1400 with Modbus and it seems reasonably straight forward. After prep'ing myself with reading the manuals and reading modbus threads on this forum when it came to setting up the comms I got a reply from the power meter straight away after having to swap the A & B wires around. The reply time is approx 50ms.

I'm looking to read input registers so have setup the commands as follows to test the data retrieval before going further. I'm looking to read the Phase 1 Voltage in address 0x301 as per the Power meter modbus manual (See attached):

Command: 04 Read input registers
Data Table Address N12:0
Size In Elements: 4
MSg Timeout:4
MB Data Address: 1
Slave Node: 1
modbus address: 30001

My issue is the reply I'm getting is Error Code (hex) 81 - Modbus Exception Code 01 returned: Illegal Function.

Has anyone got any ideas why the meter is not reading my request properly?

Regards

Jonny

I haven't read the manual in detail but i cant see a register on 1 anywhere, the registers are expressed in Hex, have you converted for the correct decimal number ?

Voltage is on 0x301 or 0x1000 so should so 30769 or 34096 respectivley, unless the meter responds to requests on hex ?

Also if you just need voltage you will just need to read 2 elements as its a long, why read 4 ?

I can't see anywhere that explicitly states they are on function code 04 (input registers) have you tried function code 03, holding registers ?

Like i say, not read it in details but a few things to consider.....
 
Thanks for the reply Tragically 1969.

I have tried function code 3 which returns an illegal data address code 02 which probably makes sense now as I'm polling the incorrect addresses.

I assumed that 0x3 was the address register 30000 range and not part of the data register number hence why I was using function code 4. :rolleyes:.

I also thought that each byte was an element which is why I was reading 4 elements. Although I had suspected what you have told me though and was going to modify my requests once I received data.

I'll return to site this morning and try this. I'm sure your suggestions have put me on the right track.

Many thanks for your help, I'll keep you updated when I return from site today.

Jonny.
 
Thanks for the reply Tragically 1969.

I have tried function code 3 which returns an illegal data address code 02 which probably makes sense now as I'm polling the incorrect addresses.

I assumed that 0x3 was the address register 30000 range and not part of the data register number hence why I was using function code 4. :rolleyes:.

I also thought that each byte was an element which is why I was reading 4 elements. Although I had suspected what you have told me though and was going to modify my requests once I received data.

I'll return to site this morning and try this. I'm sure your suggestions have put me on the right track.

Many thanks for your help, I'll keep you updated when I return from site today.

Jonny.

OK, no problem, with troublesome modus slaves I always start without the PLC and just a USB to serial lead, get the right data then go from there.
 
After going to site today I was able to receive data within ten minutes thanks to your help. I had to offset the data address by one though. Once I was getting data I had quite a bit of work to do to make it readable! Thanks again for all your help.🍻
 
Hello Every One,

I need your help to sort out a problem, i have few images(Ex. 5 No's) that i want to change automatically like a slideshow, i created 5 screens and change its name by 1,2,3,4,5 from the display property.
than i called same screen no's in replace display no(Display tab in global connection). All screen is changing(like a slide show) in a runtime but the problem is that all screens are changing with the interval of 1 seconds that i want to change it with 10sec or 15sec(its my choice).

This have to be happen without PLC logic.

How can i do that....????

Thanks in advance.
 

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