Greg
Well-known member
hi:
Please refer to this diagram
So I've got a little problem. I'm working with this input module that interfaces with a PLC. My input is across pins 1 and 2, and what I'm trying to do is count pulses (0-24V, max 500Hz). Apparently this input signal has some kind of carrier around 2kHz, which can be changed to a higher frequency if necessary. This carrier is messing up the pulse counter, so I was thinking about adding a low pass at the input to only allow the pulse to get through.
I was thinking about using a basic RC filter, but I doubt that would get rid of all the 2k hash. But it might get rid of enough. The other concern I have is the loading an RC network will have on the previous output stage, which I don't really know much about. Ideally, I'd want to keep the RC filter with a fairly high input impedence.
Also, the input requires 7mA for the device won't operate properly.
Any suggestions? Good idea? Bad idea?
I have feeling PRR is going to lay down the law on this one... :green: .
Please refer to this diagram
So I've got a little problem. I'm working with this input module that interfaces with a PLC. My input is across pins 1 and 2, and what I'm trying to do is count pulses (0-24V, max 500Hz). Apparently this input signal has some kind of carrier around 2kHz, which can be changed to a higher frequency if necessary. This carrier is messing up the pulse counter, so I was thinking about adding a low pass at the input to only allow the pulse to get through.
I was thinking about using a basic RC filter, but I doubt that would get rid of all the 2k hash. But it might get rid of enough. The other concern I have is the loading an RC network will have on the previous output stage, which I don't really know much about. Ideally, I'd want to keep the RC filter with a fairly high input impedence.
Also, the input requires 7mA for the device won't operate properly.
Any suggestions? Good idea? Bad idea?
I have feeling PRR is going to lay down the law on this one... :green: .