Weeder Digital Output Board Question

[James Sentman]

> On Jun 15, 2021, at 6:15 AM, George <ghandley at kc.rr.com> wrote:
> 
> As usual I'm way late in responding to all your help on the Weeder WTDOT output board due to several health issues that have interrupted me from getting this board to talk. Nothing real serious on the health front except I have been poked and prodded, MRIs, Cat scans  so much recently that I feel like a medical Guiana pig.

As someone who is starting to think of himself as middle aged now at 51 I can sympathize with how much the doctors like to poke around in here even without a specific issue to try to get to the root of. So I totally understand that!


> 
> So back to the Weeder Digital output board, I followed your instructions and made the circuit use the negative side for switching, and  I finally am getting some place with 4 of the 8 points working as advertised. However, four of the points continue to defy me though I've spent considerable time with them. 

That is excellent, and also frustrating! I would verify first that just manually connecting the relay cards inputs to ground makes the relays click or not. At this point it could be blown outputs on the weeder card or blown inputs on the relay card. By manually connecting the relay inputs to ground you’ll know if thats the problem, or if those work fine that way, then it’s the weeder card. (or some interconnect between them) I have seen some relay cards with multiple jumpers for the different inputs or groups of inputs. So make sure you don’t somehow have the second 4 set to a “HIGH” value for activating or something. There are so many different designs of them out there.

> 
> At this point, I think I must have a defective 8 channel relay board. I already have another to replace it, and until I do that will I know why the four bad points weren't working, or if it was the relay board at all. The present problem is that when I try to hook up the four non working points, it screws up the first four or other hard to believe issues.
> 
> For instance, I'll see12 vdc across 2 or 3 isolated output relay contacts when those four aren't even connected to anything.

The outputs should be like a switch, there shouldn’t be any voltage across them at all. If you use the continuity setting of the meter it should say no continuity for the NO or normally open, contacts when it is not energized (but should show continuity between the NC or normally closed contacts) and the opposite when it’s energized. If you’re using the meter on the voltage setting then it may be measuring anything, or even nothing, or just stray capacitance between the relay contacts on the board and the input voltage. Use the continuity setting to be sure.

> 
> I've also seen some of the 4 bad points begin operating some of the 4 working points duplicating their efforts. I haven't given up at ll, and hope the issues are all due to a bad relay board, which brings me to my real reason to write.

Well that sounds definitely frustrating and like a problem with the board. I would not leave any inputs for the controllers just “floating” depending on what kind of isolation circuits they use it might not have pull up (or down depending) on the inputs and it might turn on and off randomly or in line with other things you’re doing. If there are any relays you’re not using get a project jumper from that input to either ground or Vcc to keep the relay off or on just to be sure that isn’t the problem. However, if that really is the problem then this board doesn’t have the proper filtering on the inputs and will always cause trouble and possibly you should look at a different model. But verify that it fixes the problem by connecting all the unused inputs to either gnd or the +12v to keep them definitely on or off.

> 
> In order to get one of the bad points back online, I need to replace a WTDIO board that I keep burning out channels with nothing more than dry contacts. Go figure!
> 
> At first Terry said that was totally impossible, however  think I've begun changing his mind.
> 
> One of the fixes involves me installing a WT-DIN board in another location as I have some apparently long runs and Terry says, and I can't get it to work in the normal fashion with the plus side doing all the switching. That didn't work, so now I've begun trying using the negitive switching  system the WTDOT board uses, but so far, nothing with either wiring system makes it work. Do you happen to know for a fact that I should be using the negative switching system with this board as well?

Long runs can cause problems with the serial data, and they also make it vulnerable to things like nearby lightning strikes that will induce current on the lines. Using another wiznet card and an ethernet line instead solves some of those problems, but then it’s the ethernet jacks that may be ruined by the induced current from lightning. RS232 really isn’t good for super long runs unless you have properly shielded cable or other tiny induxed voltages from being near power lines or other things will cause stray bits. Ethernet again gets around that problem. Regardless of the connection type, rs232 or ethernet you’ll want to get some surge protectors at the beginning and ending of those long lines. Since I added those for the RS232 here I’ve had no issues with any future lightning but that one hit was not at the house and damaged nothing else except the USB/Serial adaptors at one end and the weeder board at the other. So it doesn’t have to actually cause surges on the power lines to the house to cause trouble.

When I run long rs232 lines I use cat-5e or better ethernet cables. Since the weeder cards do not use hardware handshaking you only need 3 wires, tx, rx and gnd. I ran those on separate pairs with the other twisted wire connected to ground and the unused wires in the cable connected to ground. That provides enough shielding here to make sure the data gets through. Ethernet is actually a differential serial system on the hardware side and so is even more resistant to noise which is why it works as well as it does. You could also use rs485 adaptors on each end and run differential pairs (along with the data ground) to eliminate interference on those lines. Those are cheap, but I would try making sure all the unused wires in the bundle are grounded before I resorted to that.

> 
> On this subject, I'll close here and wait to hear from you, and thank you in advance for the help.
> 

Thanks,
 James


James Sentman                       http://www.PlanetaryGear.org		http://MacHomeAutomation.com




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