02-04-2012 09:37 PM
I'm new to DasyLab and am developing an application to measure torque, rotary position, and RPM. I'll be using an Interface T8 pedestal torque transducer with a built-in rotary encoder capable of measuring angular position, speed, and direction. The encoder will be outputting 5V TTL at one pulse per degree. I'm using an MCC 1608GX USB DAQ device capable of reading analog and digital signals. I'm looking for insight on reading the TTL output from the encoder and converting it to angle and speed. Any help would be appreciated.
02-06-2012 05:22 AM
For the encoder, you need to use the counter inputs and not the digital inputs.
By this matter you will get the frequncy measuramnet of the signal. In the 1608 manual you should be able to find how to connect and setup the two inputs to use them with a full quadrature input.
Using the TTL input will requires you to run DASYLab with a sample rate that would be to high
02-06-2012 07:44 AM
Please contact Measurement Computing directly at www.mccdaq.com.
They will be able to assist with the hardware and how the MCC-DRV driver works with the DASYLab software.
If the rotation is only in one direction, event counting may work OK, but the counter cannot be read via hardware pacing (just software polling).
02-06-2012 07:48 PM
If you want to go directly to the 1608 you need to take the counter input and use it as a frequency input. This will give you the Frequency of the encoder that you can convert to RPM but I don't think you will be able to detect the direction.
To my experience the signal is not very stable due to the software pull but good enough if precision is not a question.
Another oprion is to buy an additional small frequency to analog converter that will take a dirrential output. This units can usually be programmed for +/- Frequnecy to +/- rpm.
There are models out there that are designed fo quadrature encoders. The link below is a good example.