Controlling a Freqrol With an FX-X2n

[Gary in Auburn 0]

Hello all. I am an instructor at a community college in Northern California and am in the process of developing a course for our Mechatronics program on, shall we say, a real-time basis. That is, I am attempting to learn the material and implement the course as we go, having been handed it at the last moment due to health considerations of the instructor who was supposed to have developed it over the last summer break. In other words, I have until Monday to learn what I am supposed to teach next week! The project this week is to control a three phase motor with a U-100 Freqrol, using our FX2n-32MT based trainers. We also have a small 'oven controller' simulator/trainer which consists simply of an incandescent bulb for a heat source (controlled by a solid state relay) which has both an LM135 IC temperature sensor and (as of last weeks' project) a k-type thermocouple sensor aboard. We used the thermocouple last week to control the bulb temperature via FX2N-2LC temperature control blocks. We also have FX2n-4AD and FX2n-4DA blocks available. So. The idea is simply that the oven simulator is a production process which needs temperature control, and the motor runs the cooling system pump. As the temperature of the 'process' increases, the motor speed should increase, and visa-versa. We have, as I mentioned, already implemented the input side - that is, we have used sensor input to control the bulb. I am thinking that for this project we will just have the bulb come on for, say, sixty seconds or so then go off, monitor the temperature, and have the 'cooling system' respond appropriately. The sticking point for me is that, as a newcomer to PLCs in general, I have never interfaced the U-100 with a PLC before. Looking at the manual for the Freqrol, I see that the inputs of terminal blocks one and two are controlled by parameters 59, 60, and 61. Okay, so P59 says it "...allows the acceleration, deceleration and setting clear setting operations in the remote setting box FX-FK (optional) to be done just with parameter settings". Hmm. Does 'optional' mean that I have to pay extra for the FX-FK box (which I don't have), or that I don't really need it? And the 'just with parameter setting' bit - how does that help me? I don't want to set parameters - I want to vary the settings remotely. Then there is P60... Then there is P61... Well, I could continue with specific questions, but I think you get the idea...I am pretty much clueless here. So, are there any resources about which would provide a quick-start on how to interface these devices in the simplest possible way? Sure would appricate any input. Hey, hold the phone here...in the 'Explanation of terminal specifications' chart which I have just found it says that terminal 10 is the "power supply for frequency setting" and that terminal 2 is the "Frequency setting terminal (Voltage signal)" and that the output frequency will be max when the voltage signal is 5V. Perfect! So, ahh, what kind of parameter setup is needed to make that happen? And, let's see...where would I get the varying five volt signal? Aha, perhaps the D to A converter? and, say, there is a little wiring diagram on page 20 that says if I short SD and STF the motor will run, and the terminals 10, 2, and 5 will control the output frequency. Whoa. Is it that simple? I'll give it a try... Thanks in advance for any thoughts. Gary Edited 3 Nov 2006 by Gary in Auburn

[Gary in Auburn 0]

Okay, I think I am in business, for the most part. I have set P79 to 2 to enable external control, and am (for now) just using a pot across the 10, 2, and 5 terminals to vary the frequency, with a switch across STF and SD for stop start, and it works like a champ. Now that external control is working, the next task would seem to be to transfer control to the PLC. Since I have only the PLC, an A to D block and a D to A block at home with me I am figuring to use the A to D to read the temperature and the D to A to send a control voltage. I havn't used the D to A block yet, so I would appriciate any thoughts as to the fesability of this method - and any adivce on the little 'gotchas' that seem so previlant with these systems. So, on with the show...in the morning!

[Crossbow 297]

U100 is so out of date I've never even seen one. But programming the analog modules is easier The modules actually contain their own processor and memory, and you use the FROM and TO commands in the PLC to read and write data to them. Use FROM to read in an analog signal and TO to write data to the card. Same for the 2LC card Be sure to download the manuals for both modules, as each has it's own memory map.

[FNMdeJong 7]

For progrmming the modules just see the dedicated manuals, there are some good examples of programming it. For connection of the analogue input see page 70 of the manual for a connection example. Connection between pin 2 and 5. 5V means full output (Hz). To change the input from 5V to 4-20mA see the example. By parameter 902 and 903 you can change the Bias and Gain setting of the input. Bias meaning start freq. by 0V input and gain means output freq. by 5V input. (Automatically Pr 21 and 22 will be overwrite by these settings) Next paraqmeter has to be set: Pr 60 >= 1, setting depends on the use of X1, X2 and X3. Pr. 79 = 2, means only external mode. To use the PU again you first have to set P79 again to change any parameters with the PU. Easier is only to switch to external mode with the PU, then you can easily switch back to PU or RUN mode. You need the 2LC module to read out the thermocouple!! Edited 8 Nov 2006 by FNMdeJong