Connecting AB SLC 5/03 with Siemens HMI

[VoltSmith 1]

I'm trying to connect a Siemens HMI (MP277) with an Allen Bradley SLC5/03. I understand that the channel 0 of of the AB CPU is RS232C, and can be used for HMI connection. But I'll need an RS232C-RS422 converter for it, since the MP277 doesn't have an RS232C port. A more direct connection can be made from ch 1, which is RS485, to the HMI serial port (which is selectable between raw RS485 and Profibus). Has anyone tried this? I'm connecting IF1B of the Siemens MP277 to the RJ45 on the SLC5/03. Pinout is as follows RJ45 IF1B Description 1 3 B 2 8 A 4 5 Gnd However, the devices are not communicating. I have no experience with AB platform. Is it actually possible, what I'm trying to do? Regards. Rahul

[TimWilborne 108]

You wouldn't only need a hardware converter to get it to 422 but you would also need a protocol converter to convert the AB's DF1 to the Siemens protocol. Just curious, why are you trying to tie the Siemens screen to the AB PLC?

[VoltSmith 1]

The original HMI was RedLion, and that's broken now. We want to replace it with a Siemens one. RedLion (and AB too) has no presence here; Siemens on the other hand has excellent local support and ready stock. Regards Rahul

[TimWilborne 108]

Then that is a good plan, but is it feasible to swap the AB for a Siemens while your are at it? Otherwise you will be in the same situation if the PLC fails.

[VoltSmith 1]

Thanks. Replacing the PLC will be the next step. But that step may came after three months :( We're under tremendous production pressure. In fact, we're running the machine without HMI right now.

[TimWilborne 108]

You are probably going to be ahead to either get a replacement Red Lion or until you can change the 5/03 out also. I'm not that versed in Siemens, but from what I've used it I don't think what you are trying to do will be possible. The opposite is very feasible, changing the PLC and adapting the Red Lion to run on the Siemens PLC, but that doesn't really help you right now. Do you know any places that you could possible get the Red Lion repaired at to tie you over?

[Rowan Finch 0]

What you are trying to do is indeed possible. In WinCC Flexible (I am assume you are using it for the MP277), you can select AB DF1 (RS422) or AB DH485 (RS485). For DF1 you will need a converter, but that can introduce its own problems from experience with AB DF1. As long as Ch1 on the SLC can be configured for DH485 (which it is from memory) then go the AB DH485 option. Either way, make sure that the Channel setup on the CPU matches exactly the communication settings in the MP277 communications setup. Specifically, baud rate, parity, data bits, stop bits and the one that is easy to overlook but also critical Checksum. The default checksum on the AB CPU is normally different to the default in the MP comms setup. Also, if using DH485, in the control panel of the MP277 there is a specific icon called DH485 where you need to make appropriate settings. Of course there is also the dip switch settings for IF1B to switch between Profibus and RS422/485. From my experience, it has normally been the setup of the CPU channel incorrectly that has caused most problems. Hoep that give you some things to look at.

[VoltSmith 1]

I can experiment on the system next Monday. Will update you all about the result. Cheers.

[VoltSmith 1]

The Red Lion has been repaired, and the machine is up with that HMI. But the customer still wants the Siemens piece, and I'll continue to experiment next week. Cheers.

[TimWilborne 108]

Thanks for the correction.