Connect SLC to Hyperterminal

As some of you know I'm pulling my hair out with an ASCII command in RSLogix. My plan is to connect the SLC5/03 to my PC via port0 to com1. Do I need just a serial cable with female plugs on both ends? Most have one male and one female. The second part is to connect to the drive via hyperterminal to figure out where I'm loosing my mind...

Thanks
John

To connect an SLC-5/0x Channel 0 RS-232 port to a PC, you need a "null modem" type cable with two female DB9 plug ends.

The A-B cable for this purpose is the 1747-CP3; these are extremely common among SLC-500 users, as the right-angle plug on one end fits nicely into the controller port and allows the door to close.

The full pinout, including the handshaking pins, can be found on the Rockwell Automation Knowledgebase.

Greetings John ...



you’ll need a serial cable - but there are two basic types ... “straight-through” and “null-modem” ... you need the null-modem type ... that means that the cable needs the following pins connected ...



2 to 3

3 to 2

5 to 5



there may be other connections too, but those that I’ve mentioned are USUALLY the most important ...



I STRONGLY agree with using HyperTerminal to troubleshoot your problem ... and here’s a “one-step-further” suggestion ... you might not need to go this far, but this little trick is well worth remembering for those “last straw” efforts before you give up on a project completely ...



the idea is to cut up a couple of serial cables and make a “Y” connection ... one end goes to the SLC ... another end goes to the other “device” (whatever the heck you’re having trouble communicating with) ... the last end goes to a computer running HyperTerminal ... the idea is that (depending on how you connect the wires at the “Y”) the HyperTerminal computer can now “eavesdrop” on the conversation between the SLC and the other device ...



I’ve used this approach on several “perform-a-miracle” occasions where nothing else would work ... think of it as something like using a voltmeter or an oscilloscope to troubleshoot an electrical circuit ... the computer and HyperTerminal play the part of the test equipment ...



if you’re interested in trying this, here’s the pinout that I’ve used before ... you MIGHT have to switch things around to work with your “other” device ... secret handshake: not ALL RS-232 devices use the same pinouts ...



basically start by connecting all three “pin 5” wires together ... that’s for “signal ground” ... then for the HyperTerminal “eavesdropper” computer, use ONLY the wire from “pin 2” ... that’s USUALLY the “receive” line on a DB9 plug ... then decide which end of the conversation you want to listen to ... the SLC will be transmitting on its “pin 3” ... the “other” device will also be transmitting on its “pin 3” ... splice into the appropriate wire and let HyperTerminal show you what’s being said ...



I’ve used this approach often enough that I have a special cable made up with all of the connections landed on a small breadboard so that I can easily plug things together in any combination imaginable ...



hope this helps ...

Thanks Ken,

I hooked up the null modem cable and when I send using AWA it reports that it sends xx chars but I don't see it in hyperterminal. Hyperterminal says it is connected. My settings on both ends is N,8,1 with no flow control.

Here is the configuration of Hyperterminal...




Thanks
John

Thanks Ron,

What I have is a serial cable with a null modem adapter. We have used hyperterminal to connect with the "other device" and that is working as expected... Now I need to figure out what I'm doing wrong on the PLC side...

Here is my port settings in RsLogix




I know it has to be something simple...

John

I'm going from memory here, but I think your Chan-0 System need to be set to 'Shutdown'

No, the settings for Channel 0 look correct, with the port set for "User" mode so that you can perform both ASCII writes and reads.

I'll hook up an SLC-5/05 to Hyperterminal with your settings and see what I get. I've done this many dozens of times and will try using your precise settings.

Ok, I changed the Chan0 System driver to shutdown but still no communications...

John

Thanks Ken

John

I've hooked up an older laptop to the PLC with hyperterminal just to make sure there are not port conflicts on my desktop PC...

John

basically start by connecting all three “pin 5” wires together ... that’s for “signal ground” ... then for the HyperTerminal “eavesdropper” computer, use ONLY the wire from “pin 2” ... that’s USUALLY the “receive” line on a DB9 plug ... then decide which end of the conversation you want to listen to ... the SLC will be transmitting on its “pin 3” ... the “other” device will also be transmitting on its “pin 3” ... splice into the appropriate wire and let HyperTerminal show you what’s being said ...

Click to expand...

Not a thread hijack, but this sounds like a brilliant idea, I will remember this next time when setting up serial comms. The PLC that I normally use has a trace feature, but nothing better than seeing the 'conversation' as it is happening.

Can I just take a DB9 plug and connect pins 2 and 3 to echo the sent string back into the PLC?

John

I'm really drawing a blank as to how your application doesn't work and mine does with the same parameters.

Create a program with just one rung:

XIO R15:4/EN ARL 0 ST23:7 R15:4 0

If this doesnt' read Hyperterminal text into your controller, nothing will.

Generally when I get "gibberish" there's a speed mismatch, like the Hyperterminal is set for 19200 but the SLC-5/03 is set for 9600 baud.