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I’m little confused about wiring and signal conditioning the following instrument:

http://www.skypowerinternational.com/uploads/documents/4.3351.x0.140-161_WG-Geber-firstclass-advanced_analog_eng.pdf

Connecting diagram and technical data are on pages 6 and 7.

This instrument has two output options; analog and pulse. I need to use the pulse output (they call it rectangular digital signal).

In the connecting diagram there is both F - Source and F - Sink. And in technical data it shows pulse output with pull-up or pull-down resistors.

My questions are the following:

1) Do the D and S represent a MOSFET transistor?

2) Does this instrument have 2 different pulse outputs (F - Source and F - Sink)? What could it be the reason?

3) If I use for instance F – Source output should I use GND or AGND?

4) Why do I need extra pull up/down resistors?

5) Finally I couldn't find out what is the pulse output voltage with a Vs supply voltage (15-24V). If for instance the supply voltage is 24V and I want a pulse train with 8V 0V; can I then simply use a voltage divider or should I use an op-Amp?

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Do the D and S represent a MOSFET transistor?

Yes they do.

Does this instrument have 2 different pulse outputs (F - Source and F - Sink)? What could it be the reason?

The outputs are open drain with an N channel MOSFET pulling the output to ground AND an open drain with a P channel MOSFET pulling the output up to +US.

If I use for instance F – Source output should I use GND or AGND?

F_Source is the P channel MOSFET output - it pulls-up to +US and "your" load connects to ground.

Why do I need extra pull up/down resistors?

The outputs are open source outputs and these require a load or pull-up/down resistors to convert the output into a switching voltage.

Finally I couldn't find out what is the pulse output voltage with a Vs supply voltage (15-24V). If for instance the supply voltage is 24V and I want a pulse train with 8V 0V; can I then simply use a voltage divider or should I use an op-Amp?

You can use a voltage divider to give you a pulse at 8 volts - that's probably the simplest way to do it but it all depends on what circuit the 8 volt pulse connects to.

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  • \$\begingroup\$ Andy aka, I draw a wiring schematic for both pulse outputs. do you think both wiring is correct?: s30.postimg.org/dy9sxfx69/THS.jpg \$\endgroup\$ – user16307 Jan 9 '15 at 14:04
  • \$\begingroup\$ Apart from the F_Source FET symbol being shown the wrong way round it looks OK. \$\endgroup\$ – Andy aka Jan 9 '15 at 17:20
  • \$\begingroup\$ Andy aka, many thanks. but why do you think are there diodes used for and why are the resistors recommended different values? maybe i asked many details but i'm just trying to make a sense of this diagram. \$\endgroup\$ – user16307 Jan 9 '15 at 17:24
  • \$\begingroup\$ Without digging thru the whole document I can't say for sure but the diodes are probably there to prevent the wrong polarity being applied to the transistors and/or protection against inductive spikes on long cable or relay loads. \$\endgroup\$ – Andy aka Jan 9 '15 at 21:56

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