Joe Tauser

Let's start with your second question first. Don't trigger the TCP Connect Continuously. Each time you call the block it will spool a new Connect. If there was already a Connect in progress you will destroy that effort with the new call. You just have to wait a little bit. Using my State Machine method in my Modbus TCP Reads subroutine (Step #10), first I tap the Connect block with a pulse every 100 ms, which is a long time in Ethernet land. When the socket's .IsConnected bit comes on I move onto the next step - In my Modbus subroutine, there's a lot of blah, blah, blah in-between connecting the socket and listening for the response, which occurs in Step #40 - You don't trigger the TCP Client Rx block, you enable it. It will sit and listen until something comes in at which time it will set the Response Received bit (Output D). At that point the listening stops. Whatever comes in will be in the buffer, it's actual contents are irrelevant. That's up to you to decode them elsewhere. In my program I move onto the next step and deal with the buffer contents. Then I clear it out and reset the response received bit. If you're only dealing with one device you can leave the socket connected and re-enable the Rx block. In my case I'm talking to multiple slaves so I disconnect and start the process over with a different slave ID. Joe T.

You didn't mention the model of the PLC, but I'm assuming you've downloaded the software and tried to upload the program. Unfortunately, you are basically screwed on this. There is no way to get into a Unitronics PLC and upload program without the password. The only thing you can do is start over and blow out the existing program with a new one. Joe T.

Yes, you do need to use the PID AUTO-TUNE block for PID control. Do not ask why - it is a Uni-Mystery. But you don't have to run the PID A. TUNE AUTO-TUNE function. It will work fine if you just call the configuration block on the first scan, set your own PID parameters, and then just call the RUN block. Joe T.

What exactly does this mean? Are you using a prox with magnets on a wheel? If so, you may be running into the response time of the sensor. You've got I0 configured as Pulse and Direction. Do you have a Direction input on I1? Put a scope in the input to the PLC and see what the waveform looks like. Joe T.

Probably. The pressure will track the temperature. I'd still display the value. Joe T.

If I read your response correctly, you're only heating air. You didn't say what the volume of the tank was, but for purposes of discussion let's say that 300W is plenty of heat for your temperature needs. I'm also assuming the heating element is either designed for heating air or is integrated into the tank and there's no limit on how hot it can get. Let's have some fun on a Sunday night and look at this from a thermodynamics design standpoint. I refer to the ideal gas law, or pV=nRT. https://en.wikipedia.org/wiki/Ideal_gas_law This is actually one of the things you learn in school that is useful in real life. It can be re-written as P1V1 / T1 = P2V2 / T2 . In your case, the volume is constant so it can be eliminated from the equation, so P1 / T1 = P2/ T2 . If you're doing this by the book P is in Pascals and T is in Kelvin. We'll use ambient absolute pressure and temperature at sea level as a starting point, so P = 14.7 psia = 1.01 x 105 Pa and T = 70F = 294 K. Your maximum pressure is 15 psi, which is 29.7 psia = 2.04 x 105 Pa. Now let's see how hot we need to get the air to hit your 15 psi limit: 1.01 x 105 / 294 = 2.04 x 105 / T2 . T2 = 593 K = 607 F. So what you're trying to do is possible. The gas law is a linear equation, so it really doesn't matter whether you point the loop at temperature or pressure. I would use pressure as the input to the PID loop as you've indicated this is what you care about. Adding selector logic over-complicates things. I would put a simple compare block on the temperature to disable the pressure control if it gets too hot. I took a quick look at your program and you'll want to feed the output of your Pressure loop into a PWM block for the heater. Look at the Help on the PWM block for a better understanding, but I modified some parameters in some of your blocks for you. You typically want the cycle time to be one second and the PWM cycle time units are 2.5 ms, so the cycle time value is 400. The block is looking for an input of 0-100.0%, or 0-1000 from the PID block. The RTD input will return a value with 0.1 deg C resolution, so either modify your displays or divide it by 10 before you do anything. Before you call AutoTune, manually set your Proportional band to 10.0%, or 100. The AutoTune will modify it. You called the Heater output coil O0 in two different places, which is a big PLC no-no. The coil will be in the state where it was last called; in your program this is the temperature loop. So if the pressure loop is calling for heat but the temperature loop is not the output will be off. I disabled the net in Temperature Loop for now. Your Linear block is configured correctly. Since the input to the PID block is scaled pressure, you set the Low and High limits to your scaled values. Let us know what other questions you have. I modified your program in Visilogic 9.8.94. Joe T. sp JT.vlp

This reminds me of chamber controls I did to cure rubber. First you need to define your selector rules. Which is more important? Do you really need PID control? What is the tolerance of your temperature and pressure? What type of fluid are you heating? Does it have a high specific heat like water or a lower one like oil? If it's oil or something else, what is the watt density of the heating elements? Or are you using steam? Details, details..... Joe T.

Go back and look at your sample code - My first PLC programming experience back in 1989- A Modicon P190 Available for the low, low price of $6,000.00 Then you had to buy the family specific tapes to load into it for another $1,000 - The P190 weighed about 50 pounds, and I have memories of lugging it outside to a chemical tote-filling structure at Monsanto with a very long serial cable connecting it to the $25,000.00 Modicon 584 PLC for troubleshooting. After walking uphill in the snow of course. Joe T.

Search the Help for "bootstrap". It will tell you how to get your specific model into boot mode. Joe T.

It's been literally years since I've had to work from a printed copy of ladder. Reminds me of the days when software was DOS-based and it came out using character graphics. Great tip, though. I'll continue existing as TE 5. Joe T.

The question has already been answered as "yes, the frequency on the basic HSC configuration is in Hz." Integer hertz. Little known Visilogic trivia- if you need frequency resolution greater than 1 Hz you can use the "Frequency Measurement based on HSC" function block cleverly located in the Utils->Immediate menu. It returns frequency in 0.01 Hz resolution. Very handy for speed control applications where you don't have the luxury of an encoder; i.e. a prox on a bolt sensing speed. That's actually pretty clever. 😄 Joe T.

Video is supported on HMI units that have the -B10 in the part number (the "Pro" version). It's not available in the PLC only product. If you have this, the Video option magically appears in the Media tools - Which model do you have? Joe T.

UniLogic never did run very well on Win 7 as it had to install SQL Express 2012 alongside for it to work. It runs so much better in Win 10. Submit your question to Official Unitronics Support at support@unitronics.com The newer versions of UniLogic will be able open a program made on an old version. You'll also have to update your PLC firmware, but that is not a big deal. Joe T.

I see the oldest version in "Previous Versions" is 8.0.1. Download that and see if it works. If it doesn't, contact support@unitronics.com and ask for version 4.74. Joe T.

Yes! I hadn't seen that, but here's something Ofir posted: https://support.unitronics.com/index.php?/selfhelp/view-article/remote-io---urd-0200e That information really needs to be added to the manual, but I do know that Unitronics only has so many technical writer resources. Joe T.

Additional historical information - the V120-12-R1 is really old. I checked my price sheet archives and the part number changed to V120-22-R1 back in 2006 when there was a major hardware revision. I don't remember what that was. I would not use this PLC for anything other than a trainer. As Flex says, it is "possible" to do what you want but you'll spend way more time trying to stack the data up and then getting it out the serial port. Go with any of the newer PLCs that have a micro SD card. Joe T.

@Cara Bereck Levy - Do you have the additional information on the UniStream Remote I/O? Joe T.

Send this to Official Unitronics Support at support@unitronics.com Joe T.

Do this first. It's probably got something to do with whether you have the inputs set to sinking or sourcing and what you're applying to Input 0. Are you applying +24V or a contact closure as referenced to 0V? Joe T.

You don't need logic. When you configure the input as a HSC it will start incrementing on it's own in ML 0. Download your program and try it out! The HSC value is not retained through a power cycle. If it's something you want long term you'll need to continually copy the value off to another ML and copy that value back to your HSC with the start-up bit SB 2. You You're not. Each pulse is 0.1 kW, so the value in ML 0 represents kW with an implied decimal at xxx.x. For example, when the value in ML 0 = 1234 the actual power is 123.4 kW. You can set the display format to match this. Joe T.

The newest release of UniLogic supports servo axis synchronization of up to four axis using the EtherCAT communication option. Unfortunately, you have neither. A Vision probably doesn't have the processing speed you need to get the encoders to line up. What is your number of degree tolerance for the encoder positions matching? How fast is it spinning? (Master Frequency) How fast do the axes need to sync up? Joe T.

Per the latest revision notes, this feature was recently implemented in UniLogic - I doubt that it will ever be added to Visilogic, but you never know. Joe T.

That sounds exciting. What make and model of encoder did you get? Joe T.

Unitronics distributor here. Not a Unitronics employee, so do not take my comments and opinions as the official Unitronics position. Consider yourself extremely lucky. Hopefully your distributor gave you the heads-up on long deliveries at the beginning of the year. Here in the United States, delivery has been six months on Vision products since April. Apparently there's one chip also used by the automotive industry that's causing the delay. They don't know when delivery will get back to "normal". We did receive a large shipment this month and supposedly we'll get more that will cover our backlog going back to March. They are not going to re-design the Vision to use different chips. Any new designs are in the UniStream product line. My gut feeling is we will someday get caught up. I would recommend you order additional spare parts and sit back and wait. Joe T.