SLC5 to ML1400 Swap - DH485 Questions

[gothroach]

Hi all,

I'm working on a project replacing a failed SLC5/03 with a new ML1400. I've gotten the program updated and working, all the IO changed over, but have a couple of questions about DH485 connectivity.

The existing system uses a SLC5 hooked in via DF1 FDX to a 1747-AIC, and from there DH485 to a PV900 about 2000' away. I'm having trouble finding a manual for the 1747-AIC - I'm mostly just trying to figure out how 'active' the 1747-AIC is and if I can just use a 1763-NC01 on the ML1400 (CH0, configured for DH485) to communicate or if I'm going to need to make additional changes in the program.

As far as I can tell, it's a dumb converter but I want to make sure before I get on site again. If the 1763-NC01 would work, is there anything that needs to be done on the program other than setting CH0 to DH485?

Unfortunately, it's not feasible to play around with the PV900 until I'm there to do the swap, so I'm already figuring there will be a fair amount of time working on that part of the integration.

Any knowledge someone could share would be helpful on this - I'm leaning towards it being a dumb converter as the only manual I've been able to find is simple hook-up data and doesn't mention any configuration.

Thanks!

 

[OkiePC]

Is there another 1747-AIC mounted near the PV900?
Are there any other devices on the DH485 network?

 

[Ken Roach]

Double-check to see if you've got a 1747-AIC (dark gray box with modular jacks), or a 1761-NET-AIC (light gray box with speed selector dial and RS-232 ports).

Does it plug into a network port on the SLC-5/0x controller, or into the RS-232 Channel 0 serial port ?

In general, both of those are "dumb" converters that only handle signal level conversion and isolation, and do not attempt to convert between protocols. If you're connected to an SLC-5/0x serial port, then that port must be configured for DH485 itself, not DF1 Full Duplex.

If this were a short cable run, I would endorse the 1763-NC01 cable.

But one drawback of the MicroLogix 1400's RS485 port is that it's non-isolated, and 2000 feet of cable can pick up a lot of noise or connect two devices that aren't referenced to the same ground. I would use an isolator if possible.

If you have the 1761-NET-AIC then you can connect it to the MicroLogix 1400's RS-232 ports.

If you have the 1747-AIC then I'll have to check the 1763-NC01 instructions to figure out how to make a connector between that and the 1747-AIC.

 

[gothroach]

Is there another 1747-AIC mounted near the PV900?
Are there any other devices on the DH485 network?

The PV900 is the only device on the network, and it does have a 1747-AIC interface connected to its RS232 port. I believe it's a DH485 model, but the pictures I have don't show the full part number.

 

[Ken Roach]

You're getting some bad information from your client, and/or this system is set up to work only by coincidence.

You cannot connect a 1747-AIC to any RS-232 port. It does not have RS-232 ports of its own.

The 1761-NET-AIC is a device with a similar functionality, but different hardware. That *does* have RS-232 ports.

It's possible that the subject system has two 1761-NET-AIC interfaces and a PanelView with DF1 Full Duplex. This will work, but only by coincidence, because the 1761-NET-AIC is by design a half-duplex device.

Ask your customer for more photographs or precise information.