02-26-2013 03:28 AM
Hi,
I am doing a test system and I have several signals that control motors. They use PWM with a max frequency of 5 kHz.
I would like to know if with a USB DAQ or a PCI DAQ for example PCI-DIO96 could I meassure the duty cycle of these PWM signals. I mean I need to meassure with 10kHz at least.
Which are the read frequency of these systems?
Due to the high number of I/O to test I am also thinking of using Compact-RIO with different I/O modules. What do you think?
Thanks in advance
02-26-2013 08:44 AM
The DIO-96 cannot be used. It is static digital. You want a DAQ device with a counter input. You should contact your local Sales Engineer to discuss specifics.
02-26-2013 09:49 AM
They have the event trigger action function
Rising edge: start counting
Falling edge: stop counting for duty cycle and calculate duty cycle
next Rising edge: restart counting and calculate frequency
Must the count be done by a counter in the DAQ? cannot it be done by the PC?
02-26-2013 10:58 AM
I wouldn't think so with a pc clock resolution of 1ms.
02-26-2013 07:25 PM
If your PWM frequency is 5 kHz and you want to measure duty cycle to 1%, then you need timing resolution of 2 microseconds or faster.
The USB-6343 has hardware timed DIO at up to 1MHz, so it might be suitable. There are other devices with hardware timed DIO at rates of 10 MHz or faster as well.
Before you buy, determine how often you need to measure the duty cycle to make sure the data transfer can keep up. USB can sometimes be a bottleneck.
Lynn