LM393 should do the trick nicely. You can even throw in some hysteresis for good measure.I need a circuit to convert 0vdc to 24vdc and vice versa. The output needs to drive a discreet input to a PLC.
Thanks in advance for any assistance.
JM
LM393 should do the trick nicely. You can even throw in some hysteresis for good measure.
Fast, It would be nice if I could use a relay.How fast do you need the transitions to be?
I forgot to mention I need to use a solid state device.Fast, It would be nice if I could use a relay.
Thanks
"Fast" is not a suitable specification.Fast, It would be nice if I could use a relay.
Thanks
In a PLC system the inputs are scanned periodically. 5 msec would be a typical scan interval. Events which happen faster than that are invisible to a PLC."Fast" is not a suitable specification.
Is 1 ms fast enough?
Is 1 µs too slow?
How fast is "fast"?
It matters because the LM339 is open-collector and so it has to be pulled up externally. The speed with which that happens is going to depend on what is connected to that node, particularly any capacitance on it.
The switching time for the circuit doesn't matter because this isn't the source. The signalIn a PLC system the inputs are scanned periodically. 5 msec would be a typical scan interval. Events which happen faster than that are invisible to a PLC.
After saying that the switching time for the circuit doesn't matter, you then say that the prior solution wasn't acceptable because the switching time was too slow. So it would seem that switching time does matter.The switching time for the circuit doesn't matter because this isn't the source. The signal
source is a ultrasonic sensor which is suppose to output 24vdc when it detects a sheet of paper. But the sensor
that my client has outputs 0 volts dc when it detects a sheet of paper. he tried to use a relay but the relay
switching time is to slow. I'm trying to help him remotely.
Thanks again.
JM
1ms will work.After saying that the switching time for the circuit doesn't matter, you then say that the prior solution wasn't acceptable because the switching time was too slow. So it would seem that switching time does matter.
How slow is too slow?
How fast is fast enough?
The industry standard is 24 V.What is the maximum voltage on an input of the PLC? 5V or 24V?
If 5V then the pullup resistor should go to 5V not 24V.
See post #13
Would the PLC need a pullup, meaning could it be programmed into the PLC?The industry standard is 24 V.
This assumes that the PLC has internal pullups. Is that typically the case?If the sensor and PLC share a common ground seems like a simple transistor inverter should work.
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