Serial Cable Questions - please help!

[rdmpe]

I'm going to the surplus store this morning to pick up the cable parts today for connection to my AC Jr. I have a couple of questions...

- Is the minidin8 connector on the cable the MALE side?

- I have a bunch of serial cables laying around the office that came with computer UPS units. Can I just cut the end off one of these serial cables and put the minidin8 end on it? I am familiar with the pinout shown on the neptune web site.

- If I do have to buy both ends and the wire, will any shielded 8 conductor cable be OK?

Thanks!

 

[Lutefisk]

Hi,

I'm not the final word (like Curt) but here is my 2-cents.

Yes, you need the MALE connector

The problem with some "specialty" serial cables is that they are not necessary wired straight through and may have pins jumpered. I know that can be true with older APC UPS cables.

My suggestion - buy the connector and solder an 8-conductor cable to it. I would not worry about the DB-9 connector (9-pin RS-232 connector). Instead. I would lean towards terminating the cable to a terminal strip Link to Radio Shack 8-position terminal strip.

Yes, basically any 8-conductor cable will be OK and while shielded won't hurt, from what I understand about the signal levels involved shielding is not necessary for the external switch operations but might be helpful to avoid inducing electrical "noise" into the controller itself. As always, the path and location of your wiring will make a difference.

Avoid running parallel to AC wiring and cross at right angles if necessary.

Paul

 

[Lutefisk]

Dang,

I just realized that you were wanting to wire a serial connection for programming and monitoring your AC Jr.

Everything I just wrote was about monitoring external switches.

Let me try that again.

You need a male 8-pin mini-din and a DB-9 serial connector.

I would suggest buying a cheap 9-pin RS-232 cable. It shouldn't cost too much more than buying the parts and you wouldn't need to solder at the DB-9 end. (Most PC's require a female DB-9 mate with the built in male). You could take an Ohm meter and test one of your UPS cables to ensure that no pins are jumpered.

Yes, shielding will be important with RS-232 although for short distances that are not near AC lines you could get away without shielding if necessary.

And, since you're connecting right to your computer forget all about the terminal bock.

I'm sorry about the confusion.

Paul

 

[rdmpe]

Thanks Paul - no problem on the confusion, not a biggie.

I'll also try to verify that the UPS cable is shielded as well as wired straight through.

 

[Lutefisk]

Not just wired straight through, you will also want to check to see if any of the pins are jumpered. This will take a little more work.

If you straighten a SMALL paper clip you can push it into the connector and then take your reading off of the paperclip - most Ohm meter probe cables won't fit into a DB-9 connector.

If you've got plenty of UPS cables just verify which end you need and cut the unneeded connector off and use the wires and a paper clip to identify the "pin-out" and to check for any jumpering in the molded connector.

You headed to Skycrafter?

 

[rdmpe]

Hey - just got back from skycraft. I got their last minidin8 connector I would have been so if they didn't have any! I did find one cable with a minidin8 on one end, but didn't buy that one.

I fogot to stop by my office to grab the APC serial cable, so I just bought one at skycraft for $2. The connector was $1.50 so probably cost me more in gas than in supplies.