Communication with flow meter

Hello all

Thank you for the this guide really helpful.

I encountered this issue also when try communication with my flow meter.

I am using the Modbus ET200S card 6ES7138-4DF11-0AB0

What I did to solve the issue is that.

a) Change A / B cable. My work setting now is

Modbus card(A) to (Flowmeter)B and Modbus card(B) to Flowmeter(A)

b) I also change my function code in my program to FC03

Even though in manual mentioned FC03 - Read Output Register,

But this I think also depend on the flowmeter. In my flowmeter manual got mentioned need to use FC03 to access the register

Hope some info helps

Regards,

Faizal

smiffy

The master will periodically send requests to the slave - This is known as polling.
When the slave receives the poll request it will perform the following checks:-
i) check the CRC, if correct continue, otherwise the request is ignored
ii) check which slave address the poll is intended for, if it maches the slaves own address it continues, otherwise the request is ignored
iii) check the function code is valid and supported by the slave, if it is, continue, if not, an error exception response with error code 1 is returned
iv) check start address and amount of data to access is within the slaves address range, if it is, continue, if not, an error exception response with error code 2 (or somtimes 3 for the latter) is returned
v) the request has passed all checks so the slave returns the requested data / performs the requested action

So no response from the slave could be being caused by either i) or ii).

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Split from CP 341 ERROR 0830.

Please share the brand and model number of the flow meter that uses reversed RS-485 driver labels.

The EIA 485 specification does not clearly identify which line is (+) and which is (-), so some vendors do it one way, others the opposite way.  

I try to keep notes on which vendors and models do not use A to A/B to B, 

Hello Danw,

I am using Clamp on Supmea Flowmeter sup-1158j

https://www.supmeaauto.com/ultrasonic-flowmeter/1158-j-ultrasonic-flowmeter#:~:text=SUP%2D1158%2DJ%20ultrasonic%20flowmeter,performance%20and%20long%20lasting%20life.

Regards,

Faizal