I am developing hydraulic torque-turn test machine and need to control it, as well as record individual torque graphs. Control panel will utilize Industrial Joystick (to control 5 proportional directional hydraulic valves) and also requires pressure/flow adjustment mechanism (to control solenoid-type pressure and flow regulators). Another part is recording - I need to record and report individual torque graphs, but torque values for each individual test are run-time user-defined and system must "fire" dump valve very precisely (real-time) at predetermined torque value (the system will read load cell input) and stop the system once the desired torque is reached. I will also have turns counter sensor, pressure sensors etc. in the system.
I will definitely use LabView, but I am not sure whether CompactRIO is the best device for control and data aquisition in my case or I need something else. I am not sure how CompactRIO deals with run-time changes and PWM (for proportional valve controls). Any help will be much appreciated.
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I appologize for the incomplete information, but I am not extremely skilled in this science and trying my best to learn as much as possible. I am very thankful for your help.
Here are some more particulars about the system I am developing:
I need 16 PWM in / 16 PWM out in order to control 7 dual-solenoid and 2 single-solenoid proportional valves. This is controlled by PWM Joystick and PWM spring rollers (neither of them is capable of driving the valves on their own). Timing on the valves is not critical - it is just a machine's basic hydraulic control and it is open loop.
On analog side, which will be software controlled (LabView) and very time-critical, I will need 1 channel for Load Cell (to read torque) and 1 channel for the encoder (to measure turns). Sampling here should be as high as possible and these parameters should be as close to real time as possible.
Once desired torque is reached, the system should send current to the "dump" valve, which should drop hydraulic pressure and stop the machine instantly (in order to prevent over-torque).
I will also be measuring system pressure and flow through pressure / flow sensors (two additional inputs), but it is not critical either.I hope this is more clear now what I am trying to do. I would greatly appretiate your input.
I would think that the CompactRio may be a good solution for your program. You could look at something like the CRIO-9014 along with the 9104 as you controller and chasis (with FPGA). Then you could use something like the 9425/9403 for your PWM In/Out and possibly the 9237 for your load cell measurement and the 9403 for your encoder measurements. For the current output, it depends how much current you will need out to determine the module. I would totally suggest a crio because it will definately do what you want it to.
Thanks Andrew for this info,
My application will be in a very harsh environment. I have checked/compared PXI and CRIO on NI website, as per Adnan's advice, but it appears to me that CRIO is better suited for tough operational conditions.
Regarding the Voltage / Current requirements, I need a max. of 24 VDC-2A (dump valve). Everything else is lower voltage (5-10 VDC, 10-300 mA). Regarding 9425/9403 module for PWM, is one module enough for my requirements - I need a min. of 16-in and 16-out?
I would greatly appreciate your feedback and help.
Unfortunately we don't currently have a CRIO module that will deliver that kind of power. For the current output you will need some external voltage source possibly controlled by a transistor (switch) . For the PWM Input Output you will need both modules, one for Input (9425) and one for Output (9403). Hope this helps.
The 9481 Relay Module can switch 2A at 30V DC. That will work for the dump valve.
As for selecting the other modules, the table in this document provides a good overview of the capabilities of C series digital output modules. http://www.ni.com/pdf/products/us/c_series_do.pdf. The same information for input can be found here, http://www.ni.com/pdf/products/us/c_series_di.pdf.
Don't forget to consider the speed of the modules you plan on using for PWM.
[Edited to add links]
Thank you both for this input. You people on this forum are wonderful, I just wish there is comradery like this in every industry.Regarding 9403, I apologize if I am mistaken, but I thought it is both input and output module. Is it the case that you cannot mix PWM inputs/outputs on the same module or am I way off?