Flex727

I've run across a situation which may be the same as this, or at least somewhat similar. When I am engaged in program development with a project with a lot of images, after repeated downloads of the project for troubleshooting, the images on the PLC somehow get corrupted. This only happens after a large number of project downloads when there are a lot of images on the PLC. I have found that if I load a blank project onto the PLC then re-download the original project, all is well again. Nothing else I have found will correct the corrupted image problem.

Cara, you always make me smile.

Never say never! I was surprised to find a mini-USB port on a V570 that just arrived in our inventory. While trying to figure out where to find a driver I stumbled upon this very old thread. Now, if we could just get online editing, a PLC simulator, and 640x480 resolution on a V570, I will be in heaven. By the way, I installed the driver, per the instructions in this thread on my Win7-64 bit laptop (using Visilogic 9.4) and everything went smoothly. The USB port appears to work properly - I was able to connect to the PLC, but I haven't tried downloading a program yet.

This would be a great topic for a Webinar! This aspect of Unitronics networking has never been covered.

You've probably already checked this, but confirm that the COM port didn't change. Go into Device Manager and check which COM port your USB-Serial Converter is using and make sure it matches the one in the VisiLogic Communication Settings. Also, while you're there, make sure the USB-Serial Converter is enabled and functioning properly in Device Manager.

If it's just more I/O, configure the program with the maximum number of modules you anticipate having. If there are fewer, the program will not complain or cause an error. Just make sure the configurations are identical with the exception of the number of modules. This is one of the nice advantages of Unitronics PLCs.

I been using a TRENDnet USB to RS-232 Serial Converter TU-S9 with my Win7 64-bit machine at 1/10th the price of the Digi. Works perfectly. http://www.amazon.com/TRENDnet-RS-232-Serial-Converter-TU-S9/dp/B0007T27H8/

My original thread seems to have been hijacked, so just in case my remaining question has been overlooked I'll repeat it - I really need an answer:

Sorry to be so dense, but I'm still not understanding the workaround. Cara, you said, "Until we issue a new OS, save the values again after the power up scan." I don't understand what this means - EVERY scan is after the power up scan. Furthermore, saving the values doesn't appear to be the problem (at least a file is created, though maybe it's garbage), it appears to me to be the upload to PLC that's not working correctly. Perhaps my understanding of the issue is faulty - can you explain in more detail? This issue is important to me and I need to understand exactly what is going on. I have a number of PLCs at customer sites with very specific configurations that would be very difficult to reproduce manually. I have always saved the operands to the SD card (along with the application, etc) in the event of some catastrophe to allow the customer to return his PLC, new or otherwise, to the correct state quickly. Are those operand files flawed, or do I need a specific upload procedure?

I greatly appreciate the followup on this, but I'm still a bit confused. Is the answer that the Operand upload from an SD card feature has a bug and that it is now resolved in Visilogic 9.5.0? If so, is there a practical workaround for programs written with Visilogic 9.4.0?

"What if I include this same coil several times in a scan? Would it count quicker than normal?" Yes it will, as Simon said, but you should adhere to the practice of never have the same coil more than once in a program. That is bad, bad ladder logic programming. One exception to this rule _might_ be when there is a program set up for multiple configurations where the coil might exist in two (or perhaps more) different subroutines that will never both be called.

Strangely, I've found the 2GB Sandisk cards to be the MOST reliable with these PLCs. There are a couple of things to try. 1) Format the card in a desktop PC instead of a laptop. 2) Use the free Panasonic SD card formatter to format the card first, then use the Unitronics SD Card Tool after. Until recently, I had lots of problems with SD cards and Unitronics PLCs. Since then, I've upgraded to Windows 7 64-bit and VisiLogic 9.4.0 and now no more problems. I'm not sure which of these solved my problems or if it was something else.

Thank you, Emil.

Thank you, Cara!

Any answer as to why the basic Operand Upload to PLC from SD card has that strange behavior?

I have a situation where I am installing software on several different V570 PLCs - the software is the same but there are certain configuration variables that are different for each machine. I thought I could save some time while at the customer site by installing the software on a V570 PLC I have here, configure the PLC, store the Operands by downloading to the SD card and repeat for each configuration. Then I would do the upload at the customer site to quickly configure each PLC. While testing this out I find it works well, but only under a very specific situation. When I upload the Operands to the PLC from the SD card, they are totally ignored unless I Initialize the PLC first. Not only must I Initialize the PLC, but it must be done from INFO Mode on the PLC. Initializing from the Connection menu item in Visilogic will not work - yes it Initializes the PLC, but the Operand upload is still ignored. Anyone have any idea why this is? By the way, I am using Visilogic 9.4.0 on a Windows 7, 64-bit laptop, and new V570 PLCs with up-to-date firmware.

What a terrific post, Damian. I do all of the things you discuss, basically from a process of dicovery after having "bad" things happen. Buffering was an early discovery after a customer completely miswired the I/O after providing me with the specification - the process of fixing my program to match the wiring made me realize there was an easier way and I decided never again! I'm so glad to see validation from experts that this technique is both appropriate and often superior. I've been requesting a Unitronics webinar on best programming practices, tips, and tricks for some time now. I/O buffering should be front and center, as well as data organization. In the meantime, perhaps we could find a place in this forum to gather best practices in order to learn from each other and provide a valuable resource for newbies.

- Make sure PC is on the same subnet as the PLC address. - Use socket 1, port 20256, at least initially until you work out all your connection issues. - Some PC firewalls can get stubborn and will want you to be on the 192.168.1.xxx subnet - try that (on both PC & PLC) if you aren't already. - Check your cables. You need a crossover cable unless you're using an ethernet switch. - Check your System Bits 141-150 to confirm that the ethernet card is present, initialized, socket initialized, etc.

Thanks! I'll go through the configuration carefully and if I don't find the issue I'll post.

Thanks for the reply, Joe. Yes, they're all tied to a common ethernet switch - I should've mentioned that. The arrows in my picture were intended to denote line of communication, not actual ethernet cable. I used different actual port and socket numbers than you mention, but that is exactly what I did. I initialized two sockets in the Master/Slave PLCs with different port numbers and initialized a single matching port/socket in the Slave-only PLCs. Those PLCs communicate properly and exchange data. In the top Master PLC (the V1210), I initialized two sockets/ports, one for each of the Master/Slave PLCs (#2 & #4) and had one of the ports set as slave and the ScanEx block. The sockets initialize and connect and show as connected on all PLCs, but the Master/Slave PLCs (#2 & #4) do not respond to #1 with a TXD, though they show RXD from #1. There are so many settings that have to be exactly right across all the PLCs that it's very easy to miss something or make a typo that's difficult to find. I guess my primary question is, is this theoretically possible and it's not working because I have a setup issue, or is the situation of a single PLC acting as Master to one PLC, but Slave to another - and exchanging data with both - not a capability I should be expecting?

I'm having some difficulty getting communications between several V570 PLCs. My desire is to have two Masters that each talk to a single slave (but not to each other directly) and have a 5th PLC acting as Master and talking to the two Master PLCs but treating them as slaves. I'm using MODBUS IP to communicate. I have had no problem getting all PLCs to communicate with a single Master and 4 Slaves, but can't get this arrangement to work. See attached drawing. I can get PLC2 & PLC3 talking to each other and PLC4 talking with PLC5. When I attempt to connect PLC1 to PLC2, they connect just fine (both PLCs show they're connected), but they won't exchange data. PLC1 shows a TXD to PLC2 but no RXD from PLC2. PLC2 shows a RXD from PLC1 but no TXD to PLC1. Is a V570 acting as both Master to one PLC and Slave to another not possible, or do I just have something awry in my setup? Other possibly important info: PLC1 is actually a V1210. PLC2-5 are V570s. I am using Visilogic 9.4.0 and Win 7 64-bit.

I'm pretty sure you can do this in INFO Mode on the PLC.

Use the LDI[MI] function (Load Indirect MI, under the Store menu) and increment the pointer from the first MI to the 100th MI and sum them as you go. Should be able to do it in about 3 or 4 lines of code, depending on how you want to trigger the routine.

I notice both Disable View and Marking View are available options on the Binary Image Switch element in the HMI menu. When I try them they do not seem to do anything - are they supposed to? Or am I doing something wrong? They work quite nicely with the Binary Text Switch.

I don't know if Stein Yair is still around and participating in this forum, but I just want to say thanks. I had an urgent need for some random number generation and the above post is exactly what I needed. By the way, Unitronics should consider adding a RND function to the available math functions in VisiLogic.