Serial communication AC500eCo plc with power meter via modbus RTU RS485 on COM2

Hello ABB,

I'm trying to communicate my plc to power meter. But I just receive 0 zero from the slave. How can I check that my plc connected to power meter or not. Here is my program is it right or wrong?

and here is COM2 configuration setting

read data

and finally can you please explain me this /%MWX/ ?

Regards,

Comments (1) New comment

altynbyek.B Rank: 1449

Asked 8 months ago

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Here is the library use it if you don't have it

Regards

Amal

Comments (6) New comment

Amal Rank: 84

Answered 8 months ago

IEEE754 library_P.zip

Answers

Hi,

Please ensure these things

1. Configuration of the Modbus RTU (COM2) configured as per the configuration of Modbus slave device (baud rate, parity, stop bits, etc)
2. The device ID is set as 1 in Modbus slave device as now you are collecting from only one device

Your diagram seems fine but I always choose blink function for triggering the COM_MOD_MAST

Also, check the Modbus address from your slaves manual

For checking your Modbus communication you can use Modscan which is free software, you can download from the web. If you are getting the readings on there your communication is fine the problem will be with your program

You can also refer to the following post and it will give you something

https://forum-controlsystems.abb.com/...

Regards

Amal

Comments (13) New comment

by altynbyek.B Rank: 1449 on 6/17/2020 11:33:55 PM | Like (0) | Report

Thank you for your answer @Amal.
I'm sorry I'm just a freshman, so I cant understand this %MW0.0

Amal Rank: 84 on 6/17/2020 11:56:50 PM | Like (0) | Report

%MW0.0 is addressing the memory word in ABB PLC

you chose array I have chosen the internal memory to collect the data. In my case, I'm getting 32bit Float values from my slave device so I just did the conversion of float to real by combining two 16 bits

Amal Rank: 84 on 6/17/2020 11:58:21 PM | Like (0) | Report

If you are not getting any value in PLC and you have values in meter means your communication is not correct check above things I have mentioned my answer

by altynbyek.B Rank: 1449 on 6/18/2020 1:48:43 AM | Like (0) | Report

I did everything by your answer. but still cant get any data. can you please create and send me full program?

Amal Rank: 84 on 6/18/2020 1:55:41 AM | Like (0) | Report

ok
Let me get theses details

Communication parameters
BAUD RATE, STOP BITS, PARITY, DATA BIT

your PLC and IO module if any

the starting address (Modbus address)of your meter

Amal Rank: 84 on 6/18/2020 1:57:36 AM | Like (0) | Report

also how many data you should need to collect also upcoming data in which format (float, integer, etc)

Amal Rank: 84 on 6/18/2020 2:00:25 AM | Like (0) | Report

please note communication parameters should be same for master and client

by altynbyek.B Rank: 1449 on 6/18/2020 6:31:16 PM | Like (0) | Report

Baud rate = 9600,
stop bits=1
parity=None
data bits=8

by altynbyek.B Rank: 1449 on 6/18/2020 6:34:25 PM | Like (0) | Report

Data type - integer,
modbus address
0X00(HEX)-0(DEC)-Ua
0X01(HEX)-1(DEC)-Ub
0X02(HEX)-2(DEC)-Uc

by altynbyek.B Rank: 1449 on 6/18/2020 6:35:06 PM | Like (0) | Report

power meters SLave ID =1

by altynbyek.B Rank: 1449 on 6/18/2020 9:00:13 PM | Like (0) | Report

i want get holding register 40013;

Amal Rank: 84 on 6/18/2020 9:10:43 PM | Like (0) | Report

Ok did you checked with 1000ms TIMEOUT?

Also, you didn't mention your CPU

by altynbyek.B Rank: 1449 on 6/18/2020 9:15:53 PM | Like (0) | Report

I"ve checked with 1000ms but still get 0. my CPU PM-564-TP-ETH

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Amal Rank: 84

Answered 8 months ago

I have attached the COM1 configuration and COM_MOD_MAST configuration

Please go through it and anything not clear let me know

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Amal Rank: 84

Answered 8 months ago

Timeout setting is 100, is that in milliseconds or seconds?

Comments (3) New comment

ParthibanT Rank: 42

Answered 8 months ago

Here I have configured your com2 as Modbus with your shared details in communication, I have used Ladder Diagram for programming if you need you can convert it into any. Also, I just did to read the holding reg 40013. Also as you said your Modbus values are coming in integer no conversions will be required.

You need to configure your communication between PC and PLC coz that can be only done by you.

I hope this will get you if it is not getting please try to communicate using Modscan software you can download it from the web it is a free software

just try with it and let me know the result

Comments (20) New comment

Amal Rank: 84 on 6/18/2020 9:33:34 PM | Like (0) | Report

In COM2 Modbus parameters please enable Login.It is disabled and I forget to make it enable sorry about that

by altynbyek.B Rank: 1449 on 6/18/2020 11:07:23 PM | Like (0) | Report

thank you for your project @Amal. But same response. just 0

Amal Rank: 84 on 6/18/2020 11:09:26 PM | Like (0) | Report

Can you try it with using Modscan

Amal Rank: 84 on 6/18/2020 11:10:18 PM | Like (0) | Report

Configure your MODSCAN as master and check whether you are getting values

by altynbyek.B Rank: 1449 on 6/18/2020 11:12:19 PM | Like (0) | Report

yes, I've checked with modscan and getting values from powermeter.

Amal Rank: 84 on 6/18/2020 11:14:53 PM | Like (0) | Report

check your communication if it possible try it with your com1 port

by altynbyek.B Rank: 1449 on 6/18/2020 11:34:19 PM | Like (0) | Report

rs485 to com1 is it possible ?

Amal Rank: 84 on 6/18/2020 11:37:27 PM | Like (0) | Report

it is possible just to use only rs485 pins else use a converter

Amal Rank: 84 on 6/18/2020 11:40:23 PM | Like (0) | Report

but still, I don't understand what is the problem in between your slave and master
I'm sorry.also just try with a high timeout more than 2000ms. I don't if it makes any change .just try also if you are not getting any other response from here its better to contact your local abb support team

by altynbyek.B Rank: 1449 on 6/18/2020 11:59:16 PM | Like (0) | Report

I use 2 wire (A,B) between connection of master and slave is it right? is there any other wiring solutions?

Amal Rank: 84 on 6/19/2020 12:03:47 AM | Like (0) | Report

yes for rs485 only 2 wires are needed

by altynbyek.B Rank: 1449 on 6/19/2020 1:18:11 AM | Like (0) | Report

powermeter that i used is chinese meter. is it matter to communication?

Amal Rank: 84 on 6/19/2020 1:20:20 AM | Like (0) | Report

I don't think so. If it supports Modbus RTU then we should be able to communicate

Amal Rank: 84 on 6/19/2020 1:21:03 AM | Like (0) | Report

After all you are getting the readings in ModScan

by altynbyek.B Rank: 1449 on 6/19/2020 3:37:25 AM | Like (0) | Report

read_data AT %MW0.0 := ARRAY [0..20] OF WORD; cant understand this. I'm unsure about that [0..20] array shows 20 registers value or just one registers 20 value.

Amal Rank: 84 on 6/19/2020 3:40:24 AM | Like (0) | Report

read_data AT %MW0.0 := ARRAY [0..20] OF WORD

I didn't get what does this mean. If you are talking about my program I didn't create an array

by altynbyek.B Rank: 1449 on 6/24/2020 7:47:56 PM | Like (0) | Report

Hello @Amal, thank you for your help Sir,
I've solved my issues on rs485 communication. and I've another question.
reading data is float value. So how can I convert it to real value? data located on two registers

Regards,
altynbyek

Amal Rank: 84 on 6/24/2020 9:20:47 PM | Like (0) | Report

Very glad to hear you resolved the issue.
If you can let me know what was the issue!

If you are getting float value use IEEE754_32B_TO_REAL function block and convert it to real

by altynbyek.B Rank: 1449 on 6/25/2020 3:22:35 AM | Like (0) | Report

slave device device is the reason of issue. I've changed my powermeter by another one.

Amal Rank: 84 on 6/25/2020 4:25:47 AM | Like (0) | Report

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Amal Rank: 84

Answered 8 months ago

JUST_TRY.zip

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Serial communication AC500eCo plc with power meter via modbus RTU RS485 on COM2

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