Created Date: November 06,2015

Created by: Tinker

How do I wire this output to be utilized by the tach which takes PNP or NPN inputs? Can it be done?

Yes it can be done, well, it certainly should be possible, but the manual for the CTT-AN-D24 is quite horrible. I really wish they gave an equivalent circuit diagram for the counter's input, I'm having a hard time understanding the wiring examples in the CTT-AN-D24 manual, and I have successfully used one of them!

In the example it states wiring 24vDC through a 4.7Kohm resistor to the FO terminal and DCM to ground.

I am thinking wire the FO as above and use the DCM terminal as a sourcing (?) input into the tach, is this correct?

No, that would not be correct.

It looks like DCM is also the common for the digital inputs, so you would not want to use it as an output. Also it is generally best to avoid using an NPN transistor (if you look at the equivalent schematic in the GS3 manual you'll see the arrow is pointing out of the FO optoisolator.) as a high side switch.

"Open Collector " outputs are generally considered sinking (or NPN) and you should probably wire it as such.

I'm not sure why the example in the GS3 manual specifies a 4.7K resistor, it looks like that would be too much for the CTT-AN-D24, (though it would be fine for an oscilloscope of similar) from the CTT-AN-D24 specifications:

NPN ON impedance 1K ohm max. ON residual voltage: 2V max.

PNP 4.5 to 30VDC, low level: 0 to 2VDC

Actually, the CTT-AN-D24 probably provides proper current limiting itself, I don't think any external resistor would be needed, if you set it up so that the GS3 is a sinking output.

However, like the example, one could use an external pull up, for the equivalent of a PNP output from FO (connect DCM to 0V) however, the pull up would have to be sufficiently low resistance to be able to activate the CTT-AN-D24, but not so low as to burn out the GS3's output transistor (personally I'd avoid that technique)

Created Date: November 06,2015

Created by: Langleym

I am trying to wrap my head around wiring the frequency pulse output of the drive and wire it to the inputs of a CTT-AN-D24 which will simply be used as a tach display.

The manual of the GS3 states its an open collector circuit. In the example it states wiring 24vDC through a 4.7Kohm resistor to the FO terminal and DCM to ground. This generates the square wave.

How do I wire this output to be utilized by the tach which takes PNP or NPN inputs? Can it be done?

I am thinking wire the FO as above and use the DCM terminal as a sourcing (?) input into the tach, is this correct?