RSLinx connection problem

ceilingwalker · Mar 10, 2011

Good day all. My office was recently moved to another location about 600 feet of Cat VI cable was installed to connect my desktop to a SLC 5/03. When I went online, I had no issues. For the past 6 hours it will just lose connection, for no apparent reason. I click "retry" and it goes back online. However, it still continues to lose connection. Any ideas?
Also, if I may, I have 4 plcs that I need to pull new wire for to get them to my PC. I would like to create like a work group with all the PLC's connected to a network switch, however, I don't think I can because it would require IP addresses and I don't believe SLC's and PLC-5's can be connected in that sort of a fashion, can they? My objective is to have one cable going to my desk but having all 4 plcs accessible, from my desktop. Thanks much.

Jeff23spl · Mar 10, 2011

plc5 are older than me and just worked with them few times but i don't see why you couldn't connect few slc on an ethernet network...
If they became far from reach, you may need to add switch that would boost the signal to compensate for the cable lost.

If their is nothing wrong with your network, it shouldn't broke and go back on...try po reduce the cable lenght and see or check for device making on the same network or adress collision etc...

jkerekes · Mar 10, 2011

Ethernet cables are limited to 100m per segment without repeaters and intermediate switches.

Ken Roach · Mar 10, 2011

I assume you mean an SLC-5/05, which have Ethernet ports. The 5/03 uses Data Highway 485, which has a similar RJ45 jack, but runs a completely different signalling system.

Ethernet can run for 100 meters over twisted-pair. 600 feet is about 180 meters, and you just aren't going to be able to do it.

A repeater or switch in the middle of the run would split the signal in half and make this workable.

For long network runs between floors and between buildings, network designers use fiber optics. For extremely long runs you have to use something else, like ATM or DSL or T1.

You absolutely can attach all your PLC and SLC controllers to the same network. Yes, they'll need unique IP addresses. Most enterprises at least use logically separate networks, if not physically separate networks, for the automation devices and the business computers.

ceilingwalker · Mar 10, 2011

Ken Roach said:
I assume you mean an SLC-5/05, which have Ethernet ports. The 5/03 uses Data Highway 485, which has a similar RJ45 jack, but runs a completely different signalling system.

It is a 5/03, and I use the RS232 port on the front of the processor. It works, it's just that it loses connection and I have to retry to get it back online.

A repeater or switch in the middle of the run would split the signal in half and make this workable.

Are you talking about a network switch? I have one that I haven't installed yet.

You absolutely can attach all your PLC and SLC controllers to the same network. Yes, they'll need unique IP addresses. Most enterprises at least use logically separate networks, if not physically separate networks, for the automation devices and the business computers.

So, I can install my network switch, using DH485 connection, plug each PLC into it, and access each PLC individually? How do I assign an IP address that the PLC will recognize?

Ken Roach · Mar 10, 2011

No ! Careful ! Don't !

DH485 is not Ethernet. Don't plug an SLC-5/01, 5/02, or 5/03 into an Ethernet switch; one of the pins is a +24V supply and it will damage the Ethernet port.

Ken Roach · Mar 10, 2011

Let's take a step back and do an inventory of the controllers you're actually working with and the way they are connected to your computer.

The "SLC-5/03" you mentioned in the beginning of this thread: does it really say 'SLC-5/03" on the front ? Is one of the controller LEDs labeled "DH485" ?

ceilingwalker · Mar 10, 2011

Ken Roach said:
Let's take a step back and do an inventory of the controllers you're actually working with and the way they are connected to your computer.

The "SLC-5/03" you mentioned in the beginning of this thread: does it really say 'SLC-5/03" on the front ? Is one of the controller LEDs labeled "DH485" ?

It says "SLC 5/03 CPU". The DH485 is used for the HMI (panel view) and the RS232 is what I connect to my laptop.

ceilingwalker · Mar 10, 2011

In the bottom of the control cabinet is a 1747-PIC (Personal Computer Interface Converter), is what is says. It is not connected to anything and I have never seen one of these used before.

Ken Roach · Mar 10, 2011

Okay, that makes it much clearer. It sounds like the Cat6 cable, which is typically used for gigabit Ethernet, is instead being used for DH485 or RS-232.

What exactly is connected to the Channel 0 serial port of the SLC-5/03, and how exactly does that connect to the serial port on your PC ?

If it's just copper (no signal converters) between the SLC and your computer, I'm *amazed* it works at all. RS-232 should be good for about 50 feet, not 600.

If there are signal converters, we'll discuss those.

ceilingwalker · Mar 10, 2011

Ken Roach said:
What exactly is connected to the Channel 0 serial port of the SLC-5/03, and how exactly does that connect to the serial port on your PC ?

If there are signal converters, we'll discuss those.

Channel 0 is my RS232 connection from the CPU goes to com1 of my pc. No signal converters connected to it. Actual footage of wire used was slightly less than 600ft.

ceilingwalker · Mar 10, 2011

Do you think the "close to 600 ft" might explain the "communications loss to processor" pop up? As soon as I click "retry" it goes right back online for about 10 minutes, then does it again.

Mickey · Mar 10, 2011

WOW, I have used RS232 with 150 ft of wire without problems. But 600', I'm amazed you can connect at all.

Dravik · Mar 10, 2011

Yeah, that's rs485(not to be confused w/ dh485, NOT THE SAME THING, protocol vs electrical standard),rs422 range there..

Ken Roach · Mar 10, 2011

Absolutely, yes, the communications failure is because of the very long cable. I am amazed that it works at all.

Cat6 cable is very tightly twisted, low-capacitance cable. It's actually really good for serial connections. But you're way, way over the length limit.

If we restrict our view to only the SLC-5/03 serial connection, the way to address this is to convert from RS-232 to RS-422 or RS-485 at both the PC and the SLC-5/03 end. Any "4-wire RS485" converter will work with DF1 Full Duplex protocol. I like the devices offered by B&B Electronics.

Because your goal is to network all of your PLCs, let's take a broader look at the inventory. What model(s) of controllers do you have ? Is there a chance to run fiber optics in place of the CAT6 cable ?

RSLinx connection problem

ceilingwalker

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ceilingwalker

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