Question: I have DMM which is producing pulse with duration of around few microseconds. The pulse need to be sampled in PLC, which has sampling rate of 1ms. In other words the cycle loop can't be reduced to microsecond resolution. So it's impossible to reliably detect the pulse from DMM.

Could somebody recommend a simple TTL based circuit solution, which will be able to capture that microsecond resolution pulse and convert it into millisecond resolution pulse?

[![I](https://i.stack.imgur.com/orsZq.png)](https://i.stack.imgur.com/orsZq.png)

Answer: 
TTL solution with active low input and output. R and C are calculated for 2ms output pulse width.

![schematic](https://i.stack.imgur.com/BL5ef.png)

[simulate this circuit](/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fBL5ef.png) – Schematic created using [CircuitLab](https://www.circuitlab.com/)
Maybe a diode, capacitor, and resistor?

Low input pulse would discharge the capacitor via diode.

A high input would then allow the capacitor to slowly charge back to high voltage again.

In addition a simple 74HCT14 inverter chip could be used as a buffer to drive the RCD network and again buffer the RCD output to square wave.