Joe Tauser

To answer your question - yes, the Samba only does two loops. You may want to reconsider whether you need PID at all for an HVAC system. Often people think they need PID control when on/off control will do and is much simpler. You're probably trying to control to 1% humidity, which is actually impossible because most humidity sensors are accurate to +/- 2% RH. In addition, it probably takes a while for the environment to react to the humidifier or dehumidifier being turned on, so if you turn it off when the setpoint is reached (on/off control) it probably won't overshoot. Ditto on the temperature. There are a lot of "probably"s in my comment. Let me know if I've made incorrect assumptions about what you're doing. Joe T.

Make sure your baud rate is set to 115200 if you are trying to talk to a V350. Joe T.

Try seeing what is actually happening by doing an STL View of the network - right click on the network number itself and select "STL View" from the drop-down menu. Often Visilogic will re-compile a large network and create local internal bits to run the logic. You'll know it's doing this if you see LB 0 in the resulting statement list. This is a downside of what Visilogic allows you to do by stacking outputs in series - it doesn't always work the way it looks like it should. The previous posts are probably correct - the PLC is probably solving mini-rungs and your reset of MB 49 has killed your STO block. Joe T.

Search the Help for "bootstrap" and "Info Mode". Joe T.

Use an EX-A2X, which will support up to 7 modules of local I/O. It comes with a 1m cable. Cables are available in other lengths up to 20m. Joe T.

If you connect to COM 1 with a serial cable the Visilogic PCOM protocol will override Modbus. Plug in and see what happens as Aus describes. Joe T.

Your equipment picks are a good start. I'd recommend looking at the IO-AO6X for your units with analog outputs - it has six outputs on one module. Use the IO-AI8 for your analog inputs. I'd also look at standardizing on a PLC model and stay away from the Jazz if all these are going to be networked together. Since you've already got expansion I/O in the works, I'd use a V430-J-B1 (no onboard I/O) and keep all your wiring on the subpanel. Unless you've got a good reason you haven't mentioned, running a bunch of the I/O wiring up to the door where the PLC is can be a pain in the butt. Joe T.

The Samba series is a fixed I/O unit by design. As you've pointed out, by the time you buy the CANbus card and expansion parts you'll have put yourself into V700 land if you use a fully Unitronics solution. The cheapest way to go would be to get the serial card and find a low-cost Modbus I/O module. Joe T.

The V230 is an older unit with the Standard instruction set. It's not very powerful when it comes to numbers. You'll have to upgrade to one of the newer units with the Enhanced instruction set. If you were to open a new project in Visilogic and select a V570 or bigger you could explore the floating point operations and see if they will fit your needs. If you're stuck with the V230 then you're kind of out of luck. Joe T.

It's all the way at the bottom. Joe T.

This is really a Visilogic question, but I can't move only one thread. You can force an input on or off by first clicking on it while online. The little status dialog box will pop up. Right click on the dialog box and you'll get a small menu allowing you to force the input on and off, as well as cancelling the force. Joe T.

Post your code. Joe T.

That would be a UDFB, or User Defined Function Block. These are available in the UniStream, but unfortunately not on the Vision series. Depending on how good of a programmer you are, you could write one program and multiplex two sets of data in and out of it. Joe T.

That would be the easiest way. You'll need to put a limiting resistor on your input. Joe T.

Yes, the Visions remember variable values. Except the actual high speed counter value which always resets to zero, but you can program around that with a last value buffer. The M90 fits in a 1/4 DIN hole, so I'd stick with something the same size. You haven't specified what output speed you need, though. If you've got your heart set on a Samba, use an SM35-J-T20. It technically has stepper driving built in but is limited to 1 KHz on a sourcing output. I know the specs say .5 KHz, but I've run it faster. If you want a real stepper drive, you'll need one with the NPN high speed sinking outputs. Entry level with this functionality is a V130-x-TR20, and the outputs are rated to 200 kHz. You can also get this I/O board in the V350. Joe T.

You're going to have to get a lot more specific with that question. Joe T.

No, I would tell you to roll back to Windows 2000 for true VB compatability The Creators will be back online Sunday morning. Fridays and Saturdays are holidays in Israel. Joe T.

That's one for the Creators. It looks amazingly like I problem I had when I ported an old VB6 program to Windows 7 and I didn't have a new enough version of InstallShield. Joe T.

An HMI button is like a regular input - it will be on as long as you hold it. If you only want something to happen once then use the transitional. Only call one subroutine per network. I did a search on the coils you're resetting and found you are still using them as a regular coil. Don't do this; the logic driving the regular coil will always win. If you just want the extract and retract to be complimentary then drive them with a NC of the other. I don't see anything calling your Manual subroutine, but when you do call it O0 will go off regardless of what O0 is doing, unless the clamp MB 10 is on. Then it will go on or chatter. Use MBs to communicate between subroutines, and put all your outputs in one subroutine. I like to put one output per net and stack them in order. If you're going to use Sets and Resets, make sure you keep track of where they turn on and off. It's easy to get lost with this kind of coding. I've also attached a state machine example of how to code. This method uses a numeric pointer to jump between steps and limits what can be done in each step, as only one step can be active at a time. It will require you to re-think your program but it's way easier to troubleshoot. It really helps if you draw a flowchart of your program before you start writing it. Joe T. 1311-1 JT-SRP 1.vlp State machine example.vlp

OK. Some tips- 1. Always use a positive transitional with an HMI button. You don't want the PLC to keep setting the Reset. 2. You can only use a regular coil once in your program. You've got the two outputs in question assigned twice - the status of the output will be whatever it was in the last place it was used, which can be very confusing. 3. A timer consists of two parts - the timer coil, and then contacts referenced to it. It is a common mistake to think that a coil acts like a contact. 4. I'm guessing from your logic that O1 and O3 are on as long as I1 Anti-tiedown is on. Do you want them on after that? 5. It's a good idea to keep individual output control separated, even if you use redundant logic. 6. Notice the reset of MB 8 and MB 11 when the operator releases I1 with a negative transitional if they were on. If you don't know about transitionals, check the Help. Code attached. Joe T. 1311-1 JT.vlp

Can you post your code?

Chad, Are you using a Special Function as well? Kris put the -1 in the wrong place - it goes in SI 141, not SI 140. I have no idea what happens if you put a negative number in the Special Function pointer code register SI 140. He probably made the PLC barf. Joe T.

O3 and O1 will be on for one scan. You'll never see it. What exactly do you want to do? Joe T.

I don't have an example handy, but if you get a program started I can help. You'll be using one of the Special Functions to get it. Open the U90 Help and type "interrupt" under the Search tab. Something to consider is the interrupt is rather slow - 2.5 ms. Check your scan time online (SI 0) and see if you even need it, especially if you're not worried about response time. If creating steps with a couple of timers set to 0.01 seconds will do then that is much easier. Joe T.

You can put 24V into the pot, but that's not a good solution. When I run into this I engage my engineering brain and determine what resistor I need to put in series with the pot to create a 10V drop across it. What is the value of the pot you're going to use? Something to take into account is the input impedance of the Jazz voltage input is 20K, which is rather low. You'll probably want to use a 5K pot to try to minimize it's effect. Joe T.