DA- converter in LOGO!

I have a question: Is it possible to construct a DA converter in a LOGO!?
I have a digital frequency input in a Siemens Logo! and like to convert the pulse signal to analogue.
Then it is very easy to use a PI-controller and have an analogue output signal to an actuator (valve/pump, whatever)

If this is not possible....is there some kind of P-control possible for a pulse-signal. Like on a flowmeter (+GF+ signet 515) with pulseoutput to PLC and then P-controlled to a pulsesignal to dosingpump?

If anyone knows, please advice!

John

Yes it is possible, but it is not easy.
The LOGO functions are limited to basic logic functions plus timers, counters and comparisons. They also do not have an analog output, so you will need to either parallel up some outputs and roll your own DA converter, or muck around with a serial to analog converter.
I would suggest firstly checking the flow meter and seeing if it has built in analog outputs, many of them do. The ones that don't often have an adaptor card available, or a different control module that has analog available.
Failing that, you could go for an S7-200.
If your PID control is built into a PLC, then just use the internal logic of the PLC to do the job. If the PID is separate, then some companies actually have a pulse input-analog output PID controller avaiable for this application. I know Burkert has these built into its process valves, and there should be some available as stand alone units.