rookieprogrammer

Thanks, Joe. For now, I've written a Boolean matrix that looks like I might can get by with that. It's somewhat of a "poor man's PID". Of course it never settles out. We took a swing at just what you advised with the positive and negative error calculation. And I might have to go back to that. But, at least for me, the code dynamics were getting to be pretty hairy. Trying to finish this project up, so at this point, just trying to "kill the snake"

Thanks, Cara. I hadn't looked in the project examples, as I think of PID as a function and not an entire project. But here's our situation. Normally you have a controlled value (actuator, etc.) that gets modulated to control and manipulate the controlled value (temp., level, etc). So, the actuator can be closed and opened as needed. With the stepper we give it a pulse train and that controls the speed but you can't reverse a pulse train so we have to change the forward/reverse signal based on positive or negative position error. Does Unitronics have an example for that? Looking back over my notes, I think that's where Unitronics "flat lined" in regards to knowing what to do.

I am using a 570 to control air temperature. I have a hot duct and cold duct in parallel with dampers 90 degrees offset on the same shaft such that when, for example, the hot duct is 100% open, the cold duct is 0% open; driven by an Oriental Motors Stepper with potentiometer positional feedback. A thermocouple provides the PV. I am using the PWM output from a V200 card to drive said stepper in a 2 wire config with one wire being enable, the other being direction. My problem is that except for the setpoint that is manually entered of course, all the parameters are zero. I know the PID won't work with zeros in all the parameter values. What are some reasons auto tune did not write the values to the table? I am running visilogic 9.5.0 I have also tried to find pre-written PID example routines and cannot find them under the help > example file. I also tried updating to no avail. In fact, when I click on examples, I get one folder that is "version 900" that has no PID example that I can find. Do example PID's exist? Also, is there any conversion that needs to take place between the PWM output and the stepper? I'm worried I'm in Unitronics "No man's land" as the folk I've talked to at Unitronics support who are consistently good about answering questions seem to have the reaction of family at the Thanksgiving table when the wayward relative pregnant with an illegitimate child is metioned. I can feel the loss of eye contact on the phone. Then when I don't see examples, it makes me wonder if Unitronics just doesn't do much with PID's? Thank you for ANY help you can offer! rookieprogrammer being baptized in fire

Thanks. I had given up on Unitronics. I'm actually having quite the hard time getting support. I've got a PID problem no one can seem to help me with. Will try another post. Have spoken to you guys in MA, and I'm told there is a PID "guru" in Israel, but they won't get them involved. I'm running a PID that needs to output a PWM signal to a stepper. Got the program written by a veteran programmer, but I think this might be a little beyond his experience level.

I have a 24v V570 with a negative chassis ground. For my analog inputs on the v200 snap in, it shows 0-10v input using ACM as the common. Nothing is shown on the unitronics cut sheet that shows a connection from the "CM" connection. Should I connect the "CM" to ground (negative)? Should I jumper ACM to CM to ground? Thanks!

Thanks, Joe!

Is there a "best method" way of cleaning the plug in pins (especially the female end)? My V200 plugged into the back of a V570 works intermittently. Sometimes an output will stop working. I can turn PLC off, unplug V200 and plug it back in, and it starts working. Sometimes I can just press the back of the V200 and it starts working. Is this a a quality problem of the connector, or does it need cleaning? The PLC is new although I have had it over a year. Went to training so I could learn Unitronics. By the time I'm now trying to get things to work, out of warranty. Sometimes the port 1 of the com link stops working and I have to transfer plug to port 2. Did I get a unit built on Monday morning?