I’m little confused about wiring and signal conditioning the following instrument:
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?
Best Answer
Yes they do.
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.
F_Source is the P channel MOSFET output - it pulls-up to +US and "your" load connects to ground.
The outputs are open source outputs and these require a load or pull-up/down resistors to convert the output into a switching voltage.
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.