S7 MPI Adapters

Ok, I've got a project where I have to connect my laptop to the MPI network, but I don't have access to the CPU port. The system has the main CPU, plus several other networked MPI devices. I can connect to one of these devices successfully using a 5511 card, but I would like to use one of the USP or Ethernet MPI converters instead since I only have one PCMCIA slot.

But when I looked at the Ethernet adapter (http://www.mhj-software.com/de/MHJ-NETLink.htm) it looks like I can only connect it to the CPU MPI port unless I use an auxilliary power supply, which I don't want to do. So, that leaves me with the USB adapter. Has anyone tried connecting it to an MPI device other than a CPU?

I'll contact the vendors directly, but I wanted some feedback here first. Thanks!

I have a USB adaptor.
This one also needs to connect to the CPU port.
An alternative for all un-powered XXX to MPI converters is to plug into an MPI repeater.

Doug

S7Guy,
those "other networked MPI devices" wouldnt happen to be Siemens operator panels ?
If so, there is 5V available in the MPI/Profibus port.
You can check if the Netlink and/or the USB adapter needs 5V or 24V to run.

(Sidenote: There is 24V available in the MPI/Profibus ports on the CPUs, but not in the OPs).

Oh well,

just checked the NetLink and the USB adapter, and they both need 24VDC.
So they cannot work from the MPI/DP port on an operator panel. Too bad.

edit:
S7Guy, why dont you have access to the CPU port ?
If it is because there is allready a cable attached (for the other MPI devices), then the solution is to use connectors with a PG socket (like 6ES7 972-0BB41-0XA0).
That allows two MPI (or Profibus) cables to go from the PLC to the other devices and to plug a programming device to the PG socket. The PG socket provides connection to all the pins in the port in the CPU, including the ones with 24V supply.

S7Guy, why dont you have access to the CPU port ?

Click to expand...

Well, these are CNC machines, using an 840D controller. There is also an operator panel and an operator pendant, both on MPI, plus a remote access port mounted on the op enclosure. Due to the way the machines are set up, it will be difficult to get to the cabinet where the 840D is and run a cable across the floor (plus it's one of those union shops where I would have to find someone to open the door for me every time I need access), which is probably why they installed a remote port.

Also, another thought: Does the 5511 card and adapter also require the 24v pin? If it does, then I'm probably all set, because I was connecting to the remote port successfully a month ago. Would that mean that the remote port is connected directly to the CPU port? I won't have access to the machines for a couple of weeks, but I'll see if I can ask someone.

Does the 5511 card and adapter also require the 24v pin?

Click to expand...

No, it should work with a standard Profibus connector (without 24V).

But how do your customer connect via that remote port ? The PC adapter (Serial or USB) is so common that there is a good chance that he uses it himself. If he does, then you can too.

The customer uses a 5511 card. The problem is that my laptop only has one PCMCIA slot, and I need it for my wireless card.

If this remote port is not daisy chained from one of the MPI devices and is connected directly to the CPU port instead, it would have the 24v, right? Otherwise, I'll just have to come up with a seperate power supply.

Or, how about this scenario: I plug the Netlink into a wireless hub, and connect the MPI end to the remote port. I would then be able to connect wirelessly, which should be transparent to the Netlink. That way I could provide 24v for the Netlink with an additional plug, and still maintain portability. Make sense?

If this remote port is not daisy chained from one of the MPI devices and is connected directly to the CPU port instead, it would have the 24v, right?

Click to expand...

You will have to have a look inside the panel, how the connection is made. If it is a grey cable (like the one that comes with the CP5511 card) then there is a good chance that all the pins are wired thru.

Alternatively, try to measure between pins 2 (gnd) and 7 (24V+) in that remote port. That should clear it up once and for all.
Here is the definition of the MPI cable:


Your other suggestion of using the NetLink + an external 24V source should also work.

Thanks Jesper. I'm going to send out an email and ask someone to physically check the voltage for me. I'm also going to order one of those Netlink Adapters as well (unless anyone has bad experiences with one). I kind of like the idea that I can connect it to a hub so multiple PCs can connect to the machine.

You are probebly aware of this allready, but just to make sure that you dont get disappointed:
Only one PC can connect via the NetLink at a time.

The only "bad experience" I have heard of is that the NetLink draws so much power that it can get physically warm. Some has had defective NetLinks probably because of being installed in locations that were too hot.