Siemens comms over different IP ranges

So I've been asked to do a relatively straight forward task...

Add wireless IO to a system.

I've got all the parts, and tested setting them up and getting them working. Great, no probs (first time doing this)

However, to set up the parts onto the building wireless network, our IT staff have told us we need to change the Scalance W721 IP addresses to be able to connect. That's ok, I can do that.

But the existing PLC's in the machinery already have IP addresses set and the machine manufacturer doesn't want us to change them.

Machine manufacturer wont budge...
Our IT won't budge...

I need a solution...

The machine has 1x 1500 CPU, 3x 1212 CPU's, 1x KPT1200 HMI.

We want to add 4x Scalance W721 clients to enable wireless comms to...

1x KPT1200 HMI (remote operation)
2x Logo PLC's (these will be the remote IO's only a couple of signals to pass)

I could quite easily utilise a spare 1200 CPU or another spare Logo PLC to operate relays and pass the signals via the relay contacts in the machine. That's easy enough... but that doesn't solve the remote HMI issue.

Any thoughts or ideas?

You could possibly use a NAT router.

I'd say you really need a router... but there is no way IT is going to allow you to manage a router on their network.

In my experience, the way forward in that situation would be to contact the manufacturer to get in writing the reasons why they want it like that and also the cost to change it. It may be that there is no real reason and they just want a PO from you. So check...

If they do have valid reasons for it, then present the information to the people that requested this from you and say that you are stopped because the client has his valid reasons and IT is not addressing the problem in a constructive way. Remember that IT is there to support the business... not own or manage it as most IT staff think they do and it's ok if they don't want to go a certain way, but they need to tell you how they can achieve what you require. And telling you to go elsewhere to sort the problem is not a solution.

cardosocea said:

Remember that IT is there to support the business... not own or manage it as most IT staff think they do and it's ok if they don't want to go a certain way, but they need to tell you how they can achieve what you require. And telling you to go elsewhere to sort the problem is not a solution.

Click to expand...

+1

IT hear Ethernet and assume it belongs to them. I love it when they want to attach an SAP server to an EtherCat network...

There's a reason Cisco is poaching staff from Rockwell, I suspect it has to do with most IT degrees coming in CrackerJack boxes.

I've actually just spoken to IT about a router. We have a router in other places in the building to have a network integrated onto the building network so they can do it again. I was left with a bunch of ummmmm's though from them.

I'm going to suggest with management to make the decision and push it either way. I've done all I can for now!

I would recommend running some tests, I seem to recall that profinet traffic cannot be routed..

Oh jeez!

Could I use a CP 1543-1 card on the 1500 CPU with a different IP address from the rest of the machine network and have this purely for communications to the W721 and then the wireless network?

A few things to note:

• Profinet IO traffic cannot be routed, true, but you also need to double check how the devices are actually intending to communicate. As far as I know, LOGO! doesn't support PN. I THINK it supports S7 comms (PUT/GET), but I'm not positive. S7 comms CAN be routed. The HMI would be S7 comms as well.
• For wireless PN, siemens recommends you use iPCF, which would require a Siemens access point (with keyplug) and using the W722 client instead of the W721. For wireless S7 comms, the W721 and whatever AP should be fine.
• If IT doesn't care what the IP addresses of the machines are, and only wants you to change the W721 IPs, that's OK. I'm pretty sure the wireless clients don't need to be in the same IP range as the devices they're transmitting data for. Obviously, IT can do lots of things on their end to make it matter, but it might be a simpler request than it initially seems.
• You could add a comm card to the PLC. The CP would be fine for S7 connections. However, if you need PN data, then you need to add a CM instead.

boneless said:

I would recommend running some tests, I seem to recall that profinet traffic cannot be routed..

Click to expand...

mk42 said:

A few things to note:

• Profinet IO traffic cannot be routed, true, but you also need to double check how the devices are actually intending to communicate. As far as I know, LOGO! doesn't support PN. I THINK it supports S7 comms (PUT/GET), but I'm not positive. S7 comms CAN be routed. The HMI would be S7 comms as well.
• For wireless PN, siemens recommends you use iPCF, which would require a Siemens access point (with keyplug) and using the W722 client instead of the W721. For wireless S7 comms, the W721 and whatever AP should be fine.
• If IT doesn't care what the IP addresses of the machines are, and only wants you to change the W721 IPs, that's OK. I'm pretty sure the wireless clients don't need to be in the same IP range as the devices they're transmitting data for. Obviously, IT can do lots of things on their end to make it matter, but it might be a simpler request than it initially seems.
• You could add a comm card to the PLC. The CP would be fine for S7 connections. However, if you need PN data, then you need to add a CM instead.

Click to expand...

Thanks MK42...

OK, so it is S7 comms not profitnet, which is a bonus!

I have already had the Logo communicating with a S71212 CPU via the W721 clients and an old wireless router. So I know that works.

Your point 3 is interesting. The 4 W721 clients are connected to the wireless network. IT put in the *TOP SECRET* password and they have been assigned an IP by DHCP (I since set the IP's to static to whatever they were set at) so they are using IP 192.162.10.2XX... now if the test CPU (IP 172.25.26.200) can communicate with the test Logo (IP 172.25.26.205) then that will be our problem sorted...

I've a long weekend off starting in 35 minutes so I'll try that next week!

leem2209 said:

Your point 3 is interesting. The 4 W721 clients are connected to the wireless network. IT put in the *TOP SECRET* password and they have been assigned an IP by DHCP (I since set the IP's to static to whatever they were set at) so they are using IP 192.162.10.2XX... now if the test CPU (IP 172.25.26.200) can communicate with the test Logo (IP 172.25.26.205) then that will be our problem sorted...

Click to expand...

Enjoy the long weekend, I'm not so lucky here.

You might want to switch the W721s back to DHCP. The DHCP server could potentially reassign things later, and that might cause a conflict. Also, depending on how it is set up, the AP might not allow the connection next power-up if it isn't a DHCP client.

I'd also recommend getting IT approval for the IP addresses you're using in the PLC network, before they are connected to the IT system. It might work, but they also might get cranky later once they find "unauthorized devices".

mk42 said:

Enjoy the long weekend, I'm not so lucky here.

You might want to switch the W721s back to DHCP. The DHCP server could potentially reassign things later, and that might cause a conflict. Also, depending on how it is set up, the AP might not allow the connection next power-up if it isn't a DHCP client.

I'd also recommend getting IT approval for the IP addresses you're using in the PLC network, before they are connected to the IT system. It might work, but they also might get cranky later once they find "unauthorized devices".

Click to expand...

Long weekend over! Although it seemed quite quick (possibly due to spending half a day in bed suffering with a hangover!

Anyway... back to work!

Tried using the W721 units with assigned DHCP address, but my two PLC's wont communicate. Checked PING function on the LOGO, no reply.

So it looks like I do have to have the PLC's addresses on the same as the wireless network...

Bummer!