ac500 pm554 plc integration with proximity sensors
i ve pm554 (AC500-eco) plc with additional input module DI561 .the project requires the measurement of rpm of the spindle using proximity sensors(1 pulse for 1 rotation) . i ve connected the proximity sensors directly to one of the inputs but the plc fails to sense the pulse . max rpm i used-1000, i adjusted with varying the cycle time but i could not suceed , please help me out in solving this problem.
According to your cycle frequency of proximity sensor, DI561 Digital Input module could miss the signal. Instead of using normal Input module, you can use High Speed Counter Input Module. AFAIK AC500 Eco series support HSC as onboard IO.
For more detail about HSC, please see below Youtube link:
Hope it helps you.
Are you getting a light on input module for particular input that you have connected..If not then check proximity sensor type whwther that is NPN type or PNP type and then check PLC input type.
if this is correct then check the configuration i have attached.
If problem is still there then you need to select high speed input module.
The switching rate of the digital input is simply too fast. Theres no way that you can do this reliably with a DI module.
At 1000 rpm you would have to run the program about once every 15ms or faster to have any chance at all to count pulses - and that assumes that the DI input is true for at least half of the rotation of the shaft - and it wont be. In fact the pulse will be so short that the DI card will probably filter it out as noise.
Buy more pulse counter inout channels.
After series of trials i ve found that even though the cycle time is set to 1ms and priority to 1 in plc ,there is lot of variations in the frequency measurement using normal digital input assigned as input (pm554 i0) with setting delay as 0.1ms in configuration .I used FREQ_MEASURE FB for frequency calculation.THe application requires rpm measurement upto 16,000 rpm = 266.6666hz . Please anyone can u suggest anyother possible way without using fast counter input?