# CL57T stepper motor driver, how do you hook up the alarm?



## WobblyHand (Oct 12, 2022)

The manual isn't clear, at least to me.  The typical connection looks incorrect in Figure 4.  They have the collector of the NPN photo-transistor connected to the negative of a battery and have labeled it as COM-.  The emitter seems to be the alarm signal.  That would mean the collector is connected to positive and ALM would go to a load and then to ground.  So I'd guess that the label should be COM+?


Anyone used this signal before and figured it out?  I'm trying to work through a cable diagram for my ELS and wanted to add in this signal into the cables I make.  I am not using the alarm at the moment, but when I button things up in a box, I would like the controller to be able to read this signal, since the little light will no longer be visible.

Figures 7 & 8 don't make much sense either, they don't seem to make sense with reference to Figure 4.


Can someone point me in the right direction?


----------



## rabler (Oct 12, 2022)

I agree it looks like the polarity is wrong on the opto isolator in figure 4.      How about just checking it with an ohmmeter or an LED and 1.5V battery?  I don't see any real reason you need a full 5v for testing, although likely they have some internal current limiting resistor not shown.


----------



## markba633csi (Oct 12, 2022)

It's completely wrong.  Someone didn't have a clue
An NPN opto conventional current flow is from collector to emitter
Two possibilities:
1) the Com- is actually the two emitters and the two collectors are the outputs  OR
2) the Com- is actually supposed to be the B+ supply

Your mission Jim, is to determine which it is


----------



## WobblyHand (Oct 12, 2022)

rabler said:


> I agree it looks like the polarity is wrong on the opto isolator in figure 4.      How about just checking it with an ohmmeter or an LED and 1.5V battery?  I don't see any real reason you need a full 5v for testing, although likely they have some internal current limiting resistor not shown.


It is a simplified circuit, and there has to be a lot more there, because they claim the transistor can source or sink 100mA.  Figures 7 & 8 would indicate a standard NPN transistor output.  I think Figure 4 is utterly wrong.  It would make a lot more sense, and would match up with the latter figures if COM- was attached to the emitters and ALM and PEND were connected to the collectors.


----------



## WobblyHand (Oct 12, 2022)

markba633csi said:


> It's completely wrong.  Whoever drew it has no clue.  I'm guessing the Com- is actually supposed to be the B+ supply
> An NPN opto conventional current flow is from collector to emitter


I agree about they had no clue.  It makes no sense on several levels.  They have the "battery" negative connected to COM-.  Then the emitter would have to be connected to a more negative supply so the current would flow.  Maybe they needed a flipped version of the opto isolators with emitter up, but forgot to do this before releasing the drawing.  Clearly no electrical engineer reviewed the drawing before release.  Not only is it wrong, but it is misleading.

Well bugger.  I'll have to go measure it sometime.  Have things all apart, trying to figure out how to wire it all in a box, with connectors and stuff, so it will have to wait for a bit.


----------



## markba633csi (Oct 12, 2022)

You can test it non-destructively with a 9 volt battery and an led + 1k resistor


----------



## WobblyHand (Oct 12, 2022)

markba633csi said:


> You can test it non-destructively with a 9 volt battery and an led + 1k resistor


I figure I can test it when the cables are in place.  I still need both wires, no matter what.


----------

