Yes I called last week but I still wasn't able to make sense of jrk configuration. I posted my question on the forum to see if any users might have actually configured a jrk to do what I'm try to do. My goal (below) seems pretty common and straight forward but I'm not able to complete the configuration from the information given in the User Guide. The User Guide is oriented toward position control, not frequency control. A configuration example or two would be extremely helpful.
On page 17 of the User Guide, Feedback configuration is discussed. The Feedback configuration screen contains adjustable "Calibration" values. I can't figure out what values to put there. My application consists of a motor that I want to control the rpm (speed) in ONE direction. The rpm will go from 0 to 5000. The encoder cpr (counts per revolution) is 250. At maximum rpm (5000) the encoder pulse frequency will be 20,833 pulses/sec (5000rpm X 250 cpr X 1/60 minutes/sec). How does this frequency range (0 to 20,833 pulses/sec) relate to the "Maximum" and "Minimum" values shown in the "Calibration" column? How do I make 4095 represent 20,833? What is 4095? Is it the number of pulses per PID period at maximum speed? Also how does the information on the Feedback tab relate to the diagram on page 7? Where does feedback "scaling" take place? Does the software scale the "Calibration" values (0-4095) to "Scaled feedback" ranges of 0-2047 and 2049-4095 as required at the summing junction where the error (Target - Scaled feedback) is calculated?
Page 15 of the User Guide discusses "Input" configuration. From that discussion, and others in the User Guide, it appears that a Target value of 2048 produces zero duty cycle PWM output. But what happens if you check the "Asymetric" box move the neutral value to 0 instead of 2048? How does this impact the scaled feedback configuration? Doesn't scaled feedback range also have to change to correspond to the new Target range? Is this handled automatically by the software?
Page 16 contains a paragraph labeled "Input analog to digital conversion" . It says, "the A/D conversion panel lets you specify the number of analog samples to average together each PID cycle". But it doesn't say what the A/D sample rate is, so how can you calculate the number of samples that will fit into a PID cycle?
An example or two might go a long way in helping to understand jrk configuration. If a picture is worth a thousand words, an example can be worth at thousand explanations.
You said Jeremy's configuration probably won't work. That implies that you know the correct configuration. Please share what you think will work.
Here's what I want the jrk to do,
- Control motor speed from 0 to 5000 rpm in ONE direction using a control voltage of 0 to 5 volts.
- Prohibit reverse rotation regardless is input control voltage.
- Encoder pulse frequency is 250 counts per revolution.
How would you configure "Input" and "Feedback" to accomplish the above?