Connect devices on Modbus TCP on Modicon MBK MC80

ltavolari · ‎2022-02-02

Hi All,

I'm new in Schneider's word. I have a Modicon MC80 20310 and I want to connect it on Modbus TCP with some third party devices, using Control Expert Classic. It is possible? If yes, what are the steps? On the user guide and on Training center I've not found nothing for this case.

Thank you at all.

AlastairF · ‎2022-02-02

Yes, definitely possible.

What devices are you wanting to connect to?

What data do you want to access in the device or will the device be reading from the MC80?

How often do you want to update the data (read from the device)?

The devices will have to exist in the same network domain as the MC80 unless to connect via an external router.

The MC80 doesn't support IO Scanning or DTM's or provide DHCP service.

If the MC80 is a TCP Client then you would typically use the READ_VAR function.

See Answer In Context

AlastairF · ‎2022-02-02

Yes, definitely possible.

What devices are you wanting to connect to?

What data do you want to access in the device or will the device be reading from the MC80?

How often do you want to update the data (read from the device)?

The devices will have to exist in the same network domain as the MC80 unless to connect via an external router.

The MC80 doesn't support IO Scanning or DTM's or provide DHCP service.

If the MC80 is a TCP Client then you would typically use the READ_VAR function.

ltavolari · ‎2022-02-02

Thank you for your reply.

The device is a Third-party devices developed by my company (Barcode readers). I have ESD file for recognize it on Fieldbus.

Data sent from the devices to the PLC are strimgs of bit at variable lenght. Data Sent from PLC are Bit used for trig the device reading phase.

Update time is 16 ms.

PLC and my device now are in the same subnet.

My problem is that I don't know where I have to update ESD file and where I have to insert device in the project.

Thank you.

AlastairF · ‎2022-02-02

ModBus communications doesn't use an EDS file. That is reserved for EIP, CANopen and Profibus (as GSD file).

ModBus does use a data map so you know where the data is located in the ModBus memory map.

ModBus data is located in tables.

Old data address for read only bits is 1xxxx1 and upwards, new data address is %I0 and upwards Address 1xxxx1 = %I0

Old data address for read/ write bits is 0xxxx1 and upwards, new data address is %M0 and upwards. Address 0xxxx1 = %M0

Old data address for read only words is 3xxxx1 and upwards, new data address is %IW0 and upwards. Address 3xxxx1 = %IW0

Old data address for read/ write words is 4xxxx1 and upwards, new data address is %MW0 and upwards. Address 4xxxx1 = %MW0

Plenty of information on the web about ModBus addressing and the communication commands.
Also plenty of test tools that you can use to simulate the PLC or the field device.

Try ComTest Pro from Baseblock http://www.baseblock.com/PRODUCTS/comtestpro.htm

Also ModRSsim2 https://sourceforge.net/projects/modrssim2/

ComTest Pro will give you information on the device response time so you will be able to verify if it can respond within the 16ms. Note that the poll (request) time repetition rate is also governed by the PLC scan time. Your device is updating its data every 16ms but the PLC may only request every 30ms so you won't see every change in data point.

Also look at the READ_VAR help in Control Expert.

ltavolari · ‎2022-02-14

Really thanks,

I've solved the issue.