Beej
Member
Hi,
First time posting a question so bear with my ignorance.
I'm trying to figure out an easy way to use the pulsed output of a proximity switch to provide 2 basic functions:
1) A zero speed switch which will shut down the system if the proximity switch does not pulse at least once in 4 seconds. (OK, I think I know how to do this. ..The second one is the harder one..)
2) Measure the period between the leading edge of the pulses from the proximity switch. Details: Reading off of a 48 tooth sprocket at between 0.40 to 1.50 RPM. Very slow system.
I would like to use the calculated speed to vary the output of a variable speed drive to increase the rated speed regulation to a more acceptable level. (Approximately 0.25%) The VSD is controlled by a 4-20mA signal from a PLC. The PLC will integrate the prox speed feedback to slightly alter the 4-20mA signal from the PLC to match the commanded speed more accurately.
The VSD is a Mitsubishi FR-S510-0.4K which has a rated speed accuracy of 1% of full speed. Full speed at 75Hz is 1.5RPM. Lowest speed is about 20Hz (0.40RPM).
Any ideas?
Thanks.
First time posting a question so bear with my ignorance.
I'm trying to figure out an easy way to use the pulsed output of a proximity switch to provide 2 basic functions:
1) A zero speed switch which will shut down the system if the proximity switch does not pulse at least once in 4 seconds. (OK, I think I know how to do this. ..The second one is the harder one..)
2) Measure the period between the leading edge of the pulses from the proximity switch. Details: Reading off of a 48 tooth sprocket at between 0.40 to 1.50 RPM. Very slow system.
I would like to use the calculated speed to vary the output of a variable speed drive to increase the rated speed regulation to a more acceptable level. (Approximately 0.25%) The VSD is controlled by a 4-20mA signal from a PLC. The PLC will integrate the prox speed feedback to slightly alter the 4-20mA signal from the PLC to match the commanded speed more accurately.
The VSD is a Mitsubishi FR-S510-0.4K which has a rated speed accuracy of 1% of full speed. Full speed at 75Hz is 1.5RPM. Lowest speed is about 20Hz (0.40RPM).
Any ideas?
Thanks.