SLC 5/04 Communication Issue

[Con/Drv EE 0]

Hello Everyone:

I am trying to connect to a SLC 5/04 via a USB-1761-CBL-PM02 CABLE (see below) and it's not configuring.

I believe I am using the wrong cable but, I would like to confirm this. The RS232 port at the bottom is being used 

by the Panelview HMI. My question is: can I disconnect the RS232 cable from the HMI without stopping the 

PLC or process it is running. My task is to upload the project from the PLC.

 

 

[ElectronGuru 84]

You can disconnect the HMI but you won't have any HMI operator control over the process while it's disconnected. 

Allen Bradley controllers tend to like only Allen Bradley comm devices. You'd have a lot better luck with 1784-U2DHP adapter if you can find one. If you have to buy one, brace yourself because they're quite expensive. You'll have to set up a driver for it in RSLinx Classic.

The only auto-configuring driver I know of in RSLinx classic is a straight USB cable, like what you'd use to go from the laptop to a ControlLogix L7 or L8 controller. You might be able to configure an RS232 driver in RSLinx Classic for the cable you have, but I don't think it's going to auto-configure. You'll have to check in your laptop's Device Manager to what port it's assigned the USB end to, then in Linx you'll have to match that port, set baud rate, parity, stop bits, etc. I usually set the port number, raise the baud rate to as high as it'll go, and choose 1770...Scanport as the Device, and leave everything else alone. This works for most USB adaptors but in my experience, only temporarily. If you can get third party adapters to connect at all, they tend to drop off after a few minutes.

Hope this helps.

[alan_505 26]

What comms is the PanelView using as it may be using DH485 and the serial port may be configured as DH485 and not RS232, tell us the full part number of the PanelView and if there is any comms modules on it.

[pturmel 167]

That is definitely the wrong cable.  The circular port on a 5/04 is a DH+, not serial.  You need the 1784-U2DHP.

[pturmel 167]

That is definitely the wrong cable.  The circular port on a 5/04 is a DH+, not serial.  You need the 1784-U2DHP.

[Joe E. 262]

Generally speaking, unplugging the HMI doesn't interfere with the process itself; it just make it inconvenient to interact with it. It's possible, however, that someone at some point in some place added a sort of heartbeat of some kind between the HMI and PLC to make sure the HMI is present and running. I sincerely doubt that's the case here, but hyper-prudence suggests not unplugging it until the system is in a safe state where an interruption won't be harmful. Once verified that all is well, the system may be resumed.

As for the cables.....it's complicated. Do you have access to an offline backup of the PLC program? Look for a file with an .RSS extension. If it's an accurate backup, you can look in the channel configuration to see if it's RS232 or DH485. That will tell you which cable you need. If it's DF1/RS232, you can just use a USB-RS232 adapter (Keyspan USA19HS is my choice) with a crossover (null modem) cable. If it's DH485, you'll need a UIC adapter. My first choice for that is:
https://www.plccable.com/allen-bradley-1747-uic-usb-to-dh485/

To connect via the round mini-DIN, you'll need a DH+ adapter, which is more problematic. And a LOT more expensive. AB's version is the U2DHP, which is expensive and fragile. At my last place, we had 2 or more randomly just stop working with no visible damage or misuse. We had a large installed base of ControlLogix systems with lots of spare parts, so we had a ControlLogix chassis set up with 1756-ENBT and 1756-DHRIO modules. That made it easy...ish to connect to the SLC 5/04 and PLC5 PLCs. As a somewhat easier (but still expensive) alternative, we also had a ProSoft gateway module we used. It was a little tricky to initially set up but worked easily once working. Lasted for years. If I encountered a DH+ device here, I would seriously consider this instead:
https://www.plccable.com/allen-bradley-1784-u2dhp-alternative-usb-to-data-highway-plus-dh-anc-120e/

That one has the advantage of not needing an external power supply, which was a serious limitation of the ControlLogix chassis and the ProSoft module.