ETHERNET communication with CP476 via 3IF681.86

[alvarohconti (Álvaro Conti)]

I have a B&R CP476 PLC and would like to know how to communicate it with the 3IF681.86 module. It has an extension model 7ME020.9, in which the IF681 module is inserted. This IF681 module has two interfaces: 1x RS232 and 1x Ethernet. I was able to communicate with its RS232 interface, but I have no knowledge of how to communicate with this Ethernet.

[stephan.herbig]

Hello Alvaro,

you have to load two drivers onto the controller. You can find the files here: C:\BRAutomation\AS\System\V0240\SG3

You can find further details here : B&R Online Help (br-automation.com)

Regards
Stephan

[alvarohconti (Álvaro Conti)]

I managed to install these drivers, but how does it work for me to connect the PLC to the PC via Ethernet? I saw the manual but I didn’t really understand these IP parameters, whether to enter my PC’s IP or whether there is a default IP.

[alexander.hefner]

Hi,

I assume you’re asking for the meaning of the configuration parameters from this config dialog, right?

The PLC doesn’t have a default IP.
You can decide to set a own static IP address and network mask (not your notebooks IP, because every IP has to be unique inside a IP network) , or you can activate “Get IP from DHCP server” (then, if a DHCP server exists in your network, the PLC will get an address from this server).
In both cases, the notebook and the PLC have to be in the same IP network, because if not they can’t communicate.

The default gateway normally is the IP address from your internet router - it’s only needed if the PLC should communicate with remote networks for example with the internet or via remote access (for example, when the PLC should be reachable via a remote maintenance router) - if notebook and PLC are both in the same IP network and should only communicate to each other, then the default gateway is not needed.

The setting “IP address from node number” means: the first 3 byte of the own set IP address are used like configured by you, the last byte is set from the number you configure with the both number switches on the top of the IF card).

The “IP address and network” topic isn’t PLC specific, (almost) all devices connected with an ethernet network are communicating via the IP protocol in the same manner, and also need some of the same basic settings like address, subnet masks and so on.

If you’re new to the topic of IP networking, I recommend first to make yourself familiar with some of the basic concepts if IP networks, for example here:

What is an IP Network? A Complete Guide to Networking | RingCentral UK Blog

Here in the community, there’s also a little glossary available (but that’s not a guide, it’s only for explaining some of the most often used phrases of IP networking together with PLCs):

A tiny network basics glossary

Preamble Before you start reading, please let me point out: The following content is not “the complete knowledge about networks and services” (not even almost ), and it’s not intended to be. They’re dozens of thousands of websites out there, explaining that stuff much more in detail. I’m aware that almost everybody who’s reading this post already knows what’s a IP address, a subnet mask and so on, and has already used those things many, many times. They’re already some posts and very go…

Best regards!

[alvarohconti (Álvaro Conti)]

Thank you for your attention Alexander! So if my PC’s IP is 192.168.000.51, should I put something like 192.168.000.50 in my PLC’s IP address? And another question, should I perform any additional configuration on the Online settings screen of the Ethernet interface?

[alexander.hefner]

Hi,

@alvarohconti

So if my PC’s IP is 192.168.000.51, should I put something like 192.168.000.50 in my PLC’s IP address?

Yes, if your PC’s IP setup is 192.168.0.51 with subnet mask 255.255.255.0, the you could use for example 192.168.0.50 with subnet mask 255.255.255.0 for the PLC (as long as this address is not used yet by another device of course).

From the online setting dialog, you have 2 possibilities:
1.) to set under “Destination INA node number” the number setting of the number switches on the IF card (please ensure, that it’s not set to 0, 255, and not the number of the Source INA node number in the same dialog).
So you could set the number switch on the IF card to “02”, then it would match the setting in the online dialog like seen it your screenshot.
2.) remove the value from “Destination INA node number”, and set your PLCs IP address under “Destination IP Address”

… possibility 1 or 2 differ “under the surface” in the type, how the communication will work. I normally prefer the setting of the “Destination IP address” as long as I already know this address (which is for example not the case, if the address is delivered by DHCP server).

After setted up the PLC and transferred the configuration, please first try to PING the PLC’s ip address from your notebook - as long as the ping fails (for whatever reason, maybe cableling, maybe misconfiguration…), the Automation Studio Online setting / connection will not work.

… I really hope I remembered right about everything written above, since the CP476 is a legacy system and I’ve no longer worked with it for years. Let’s see

Best regards!

[alvarohconti (Álvaro Conti)]

Got it, I made these settings. Should I load them through another interface? And what would this PING be? A programming command?

[alexander.hefner]

Yes, you have to transfer the configuration into the PLC by a already working connection (I assume RS232)?

PING is command line tool existing in (almost?) every desktop operating system to check if an IP address is reachable.
Depending on the response of a PING command, you at least know if a device can be reached or not… just google “windows ping”, and you’ll find what it’s for and how to use.

Best regards!