Modbus RS485 to CAN configuration

Obvious question, but I need to ask anyway, have you power cycled the flow meter? Many devices need to be power cycled for any setting changes to take effect.

Try a changing the baud rate, parity, and slave address on both your Modbus software and the flow meter, power cycle to the flow meter, then try communicating again. I've seen bugs in some equipment where certain parity or baud rate settings don't actually work.

What is the vendor and model of the flow meter? Does the vendor supply PC software that can communicate to the flow meter via a USB to RS-485 adapter?
 
Did you setted properly the I-7530A-MR when doing connection test.

Which command are you using to get /send then receiven CAN MESSAGES or MoDBUS RTU command on the key in space of the test interface...

One should know Modbus RTU command properly prior to send the command for receiving the right message...

Always glad to help!
James
 
1. > I was also able to test this and we saw the same result.
And that result was ? ? ? ?

2. Modbus slaves do not broadcast, so there's a setting somewhere on the flow meter that defines whether the RS-485 port is Modbus mode or 'broadcast' mode. Have you found that setting to make sure that it's Modbus RTU?
To clarify, I meant that the built-in usb port of the flowmeter can be used to make requests over RS485 and that was not working either. The settings for the flowmeter are quite limited but straightforward and all are as they should be set in order to utilize RS485 per the manual and per the technical rep for VP instruments.

How about the Init/Normal switch located back to the device ...which position is it..
Yes it was set correctly after programming it.

In an attempt to get rid of extra item, I am only using an RS485 to USB converter to see if I get responses from the flowmeter.

Obvious question, but I need to ask anyway, have you power cycled the flow meter? Many devices need to be power cycled for any setting changes to take effect.

Try a changing the baud rate, parity, and slave address on both your Modbus software and the flow meter, power cycle to the flow meter, then try communicating again. I've seen bugs in some equipment where certain parity or baud rate settings don't actually work.

What is the vendor and model of the flow meter? Does the vendor supply PC software that can communicate to the flow meter via a USB to RS-485 adapter?
The vendor is VP Instruments. I can connect no problem to the supplied software interface. I have cycled power multiple times but I haven't tried changing the slave address or baud rate. I will do so and report back.
 
After double checking the wiring and following one of the suggestions here, I changed the slave ID and was able to get communication with the flowmeter using the RS485 to USB converter. I get appropriate responses from requests for temperature and they match the current room temperature.

I hooked the system back up to the i-7530A-MR Modbus to CAN converter and I only get a time-out response. I noticed using the 'modpoll' command prompt software that VP Instruments supplies that I don't have any issues sending commands and getting the responses. If I try to use 'Modbus Poll' I get time-out errors or checksum errors even if I am using the RS485 to USB converter, not the Modbus to CAN converter.

At this point, I think the Modbus to CAN converter issues I am having are a matter of semantics and my amateur level of understanding currently.
 
Is this the 'modpoll' you received from VP Instruments?
https://www.modbusdriver.com/modpoll.html

You should be able to get both modpoll and Modbus Poll to work using your USB to RS-485 converter - the flow meter can't distinguish between what's sending a request, so your configuration of Modbus Poll must be different from your configuration of modpoll. What command are you using with modpoll and how have you configured Modbus Poll? What is the timeout setting you're using in Modbus Poll, have you tried increasing it to 1 second or more?
 
Hello
After double checking the wiring and following one of the suggestions here, I changed the slave ID and was able to get communication with the flowmeter using the RS485 to USB converter. I get appropriate responses from requests for temperature and they match the current room temperature.

I hooked the system back up to the i-7530A-MR Modbus to CAN converter and I only get a time-out response. I noticed using the 'modpoll' command prompt software that VP Instruments supplies that I don't have any issues sending commands and getting the responses. If I try to use 'Modbus Poll' I get time-out errors or checksum errors even if I am using the RS485 to USB converter, not the Modbus to CAN converter.

At this point, I think the Modbus to CAN converter issues I am having are a matter of semantics and my amateur level of understanding currently.
Hello

I was sure that your configuration was not setted properly...
Thx for your inputs..
What is the status now..
 
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