Host Engineering Forum

General Category => General Discussion => Topic started by: Bolt on May 16, 2020, 12:51:41 PM

Title: Hall Effect Sensor to PLC Input
Post by: Bolt on May 16, 2020, 12:51:41 PM
I had previously posted this question on AD's forum, https://forum.automationdirect.com/forum/general-applications/130294-hall-effect-sensor-to-plc-input#post130295 (https://forum.automationdirect.com/forum/general-applications/130294-hall-effect-sensor-to-plc-input#post130295) before it went belly up.  Could somebody help me finish this off?

What would it take to wire a cheap flow meter like https://www.amazon.com/dp/B07RF57QF8 (https://www.amazon.com/dp/B07RF57QF8) to a PLC input, like a BRX high speed counter input? Are all hall effect sensors NPN? How can I best convert from NPN to PNP (works better with the rest of my input wiring) and maintain the high speed throughput?
Title: Re: Hall Effect Sensor to PLC Input
Post by: Controls Guy on May 16, 2020, 07:50:21 PM
If you end up with an NPN sensor, use a pull up resistor, maybe 2k.

You can always wire an NPN sensor to PNP input this way, or vice versa.  It also has the effect of inverting the input state (input is false when sensor conducts which is reverse of normal), but for counting pulses or rate in a 50% square wave you don't care.
Title: Re: Hall Effect Sensor to PLC Input
Post by: Bolt on May 27, 2020, 07:51:15 PM
This worked, thanks for nudging me in the right direction.  A 2.3K pull up resistor did the trick.
Title: Re: Hall Effect Sensor to PLC Input
Post by: Controls Guy on May 27, 2020, 08:20:17 PM
Cool!  Glad it worked!