Ren48LSD issue - totally stumped

**cobraman44** · 05-05-2012, 01:15 PM

When making a cable for just pins 4 and 5 the results are the same EXCEPT the Ren24SS does not stop working when I plug the Ren48LSD into it.
I tried reversing 4 and 5 just for the heck of it but the Ren48LSD would not work at all then. So the cabling must be correct.
It will take some for the 232 test. I cannot get the 232 cable on ren24 inside the enclosure.

**budude** · 05-05-2012, 01:26 PM

Sorry - what doesn't work with just 4/5 only? Do either/both boards work OK? (confused by "results are the same"...)

This is interesting though - I'm guessing if you reconnect pins 1/2/6 (gnd) between boards that the Ren24 will stop working again. If you have a DVM you might try measuring the difference (if any) between the grounds on both boards with just 4/5 connected.

**cobraman44** · 05-05-2012, 02:06 PM

OK Just did a little deeper checking. See if I can get it straight here

Setup#1 RS232->Ren-T(485)->Ren24SS->Ren48LSD(ONLY pins 4 and 5)
Results: Both boards work

Setup#2 RS485->Ren24SS->Ren48LSD(ONLY pins 4 and 5)
Results: Both boards work

Setup#3 RS485->Ren48LSD(ONLY pins 4 and 5)
Results: Does not work

More info on Setup#2
No Sequence running: Ground difference of the 2 boards is .12V (no jumping around)
With a Sequence running: Jumps from 0 to around 3.5V.
With Peak hold on and + on Ren48LSD 4.17V
With Peak hold on and + on Ren24SS 1.45V

So it looks like your ground theory is right on because that looked to be a swing of over 5V when a sequence is running.

**budude** · 05-05-2012, 03:18 PM

Are the Ren24 and Ren48 power supply plugged into the same circuit? Is the power supply on the Ren48 grounded (3-wire?). I can't explain this major difference in ground levels. You can run the setup as you have it in #2 but of course that doesn't fix the problem if you move things around.

**cobraman44** · 05-05-2012, 03:31 PM

Brian, I cannot thank you enough for your help. I will get to more testing when I get a chance. Today is my kids B-day party. I will keep you posted.
There has to be a reason. I just cannot let it go.

**cobraman44** · 05-06-2012, 09:56 AM

Well i cannot make it any simpler than this and still have the issue. I guess I will just have to accept that this will not work directly from my com port and use a Ren-T to drive it.
There has to be a difference I am just not seeing it.
IMG_3952 (Small).JPG

**budude** · 05-06-2012, 12:30 PM

While it won't change what you're seeing, you may want to install the 10K resistor next to PIC #1 as well as the small caps near the installed ICs and Oscillator and the 330uF cap while testing. You may (or may not) see even more oddities without them. Definitely install the 10K resistor.

Can you describe the power supply configuration in more detail - type, etc. - still there may be something there...

**pmcpa** · 05-06-2012, 12:36 PM

Looks like he's using a PC power supply (from the RYB wires I can see).... Do you have a load resistor installed?

**cobraman44** · 05-06-2012, 05:02 PM

the one in the pic is a pc supply. The reason I was using it was to test it with 5v and eliminate the PS circuit. But I have 2 12v supplies that I use with my floods and they do the same thing. I think I may just come back to this later if I really need to. I have to build 6 of these and some other projects. At least I can get them to work. Thanks again
Jeff