AC500 and Aqua Master Flow Meter Modbus RTU Communication

Dear all,

I'm trying to connect between PM585 AC500 cpu and aqua master flow meter over modbus rtu channel. I have already confgiured everything correctly -I hope :)- the communication is done using com2. attached picture show my program settings.

I did the communication with motorolla AC3680 plc and it works well with the indentical flow meter settings.

The com-mod-mast gides me the error code 8211 (time out error)!!

The only thing that I didn't use is the resistors 470ohm and 120ohm!! does that affect my work or not??!!

Hope you can help me.

Best Regards,

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engineerjaber Rank: 792

Asked 7 months ago

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Hi,

First I found in your COM2 settings is RTS Control - it must be "telegram" in order to use RS485 !

Then you have to check if the settings there (baudrate, parity, data, stop...) are the same as with your Slave 1. Are you sure the start address for reading is 5060?

Put the fixed cycle time (e.g. T#100ms and not freewheeling) for your program, where COM_MOD_MAST block is used.

Last, in my programs I always put at input of COM_MOD_MAST the variables in format, as required in the help (word, byte ...) with the corresponding INIT values (2,1,3,1000...). It is easier then for commissioning too. ADR is a must too - seems OK in your program.

Check wiring - Rx/Tx.

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kstoilov

Rank: 7

Answered 7 months ago

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Kindly see attached files

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engineerjaber Rank: 792

Answered 7 months ago

I've solved the problem. I have to use the trigger for COM-MOD-MAST enable port. :)

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by PedroC Rank: 33 on 4/4/2018 8:58:25 AM | Like (1) | Report

Hello,
I'm also with a problem trying to communicate with aquamaster via modbus 485 serial.
I'm using a usb converter with a 2 wire connection.
The software I'm using is ScadaBR and when i try to get values it says "No response from server"
I'm not using resistors, do you think that might be the problem?

by engineerjaber Rank: 792 on 4/4/2018 10:09:35 AM | Like (0) | Report

Hello,

Are you trying to read the flowmeter through a plc or directly through the scada software?

by PedroC Rank: 33 on 4/5/2018 1:07:56 AM | Like (0) | Report

Hello, I'm trying to read it directly using only a USB converter, in wich I plug 2 wire from aquamaster, Tx + and Tx -

by engineerjaber Rank: 792 on 4/5/2018 1:54:11 AM | Like (0) | Report

Hi,

You have to check all settings to be the same in both side and the same for wiring.
The issue in the aquamaster3 flow meter specially that which is a dc-operated ones, the modbus connection enters the sleep mode within 10 sec of inactivity. So in order to get new readings, you have to send two orders to the slave flow meter, the first one to wake it up and the second one to get the data.

Note that in order to read the totalizers you have to use 04 and in order to read the flow rate you have to use 03 code.

by PedroC Rank: 33 on 4/5/2018 1:57:06 AM | Like (0) | Report

Thank you, I have checked the settings and wiring for as many times as you can imagine.
I read that you were talking about resistors before, do you think that can be the problem? Because I'm using none at the moment

by engineerjaber Rank: 792 on 4/5/2018 2:03:23 AM | Like (0) | Report

I don't think so.
what data do you want to read?

by PedroC Rank: 33 on 4/5/2018 2:17:51 AM | Like (0) | Report

All the variables that I can

by engineerjaber Rank: 792 on 4/5/2018 2:21:12 AM | Like (0) | Report

I prefer o try reading the 16 bit read only integers. use code 04 and address 5060 or 1000. read only 6 words.
Be sure that the stop bits settings is 2 bits. it's default in aquamaster3.

by PedroC Rank: 33 on 4/5/2018 2:48:32 AM | Like (0) | Report

I'm trying to read with the settings you said but it still says "no response from slave"

by engineerjaber Rank: 792 on 4/5/2018 2:51:15 AM | Like (0) | Report

I recommend to implement the communication using plc.

by PedroC Rank: 33 on 4/5/2018 3:06:55 AM | Like (0) | Report

Ok thank you for your help !

by PedroC Rank: 33 on 4/5/2018 3:54:21 AM | Like (1) | Report

Engineerjaber
I have to say thank you so much because the problem was actually the stop bit
It was set to 1 and when I set it to 2 I didn't have the wires in the right place.
Now I tested again and the problem was actually the stop bit.
I think in the datasheets they don't show that, I think it's a huge problem!
Thank you !

by engineerjaber Rank: 792 on 4/5/2018 4:13:34 AM | Like (0) | Report

Good :)
Actually it's written just once in the manual :)

by PedroC Rank: 33 on 4/5/2018 4:14:40 AM | Like (1) | Report

Ok good to know, I will look for it to make sure
Thank you :))

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engineerjaber Rank: 792

Answered 7 months ago

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AC500 and Aqua Master Flow Meter Modbus RTU Communication

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