[Placement of coils on ladder rungs]

It's somewhat poor programming practice to place coils in series, and even worse to place a coil in the middle of a series of contacts. One of the nice things about Visilogic is that it allows for a great deal flexibility in this regards and will work properly even when poor programming practice is used.

 

I would separate out the logic for better readability and troubleshooting, as follows:

                             A      B

----|/|----| |----|/|----(  )----(/)---- should be broken into two nets like this:

 

                             A

----|/|----| |----|/|----(  )----

 

     A      B

----| |----(/)----

 

And ----|/|----(  )----| |----|/|----(/)---- should be broken into two nets like this:

 

----|/|----(  )----

 

----|/|----| |----|/|----(/)----

 

Done in this way the logic is clear and unambiguous.

[Visilogic 9.7.9 compatibility with older firmware]

I have a V570 PLC out in the field that needs to have some code updated. The original project, which I have, was generated using Visilogic 8.6.3. The firmware on the PLC is the firmware associated with Visilogic 8.6.3. I am currently using Visilogic 9.7.9 and no longer have 8.6.3 installed. Can I update the code in Visilogic 9.7.9 and generate a .V57 file to be delivered via the SD card, or do I need to re-install 8.6.3 to ensure compatibility with the older firmware?

[Out of memory, strange...]

I recently completed my first project with the Samba and was surprised at how limited the memory is. Just a little bit more would have been very helpful, but I took it as a challenge to get all the essential information on the screen while staying within the limitation. This was actually for a small machine (an air compressor), but the customer wanted various statistics and a log file to be displayed on screen. I really had to rework the User Interface I normally use for the V570, but I got it done and I'm pretty pleased with the result - and more importantly, so was the customer.

[Out of memory, strange...]

Samba?

[Data Table read problem]

It is bad programming practice to put instructions together in the same ladder rung that aren't conditional. The only real exception would be when you have a coil that must be activated by multiple situations, since coils should always only exist in a single net.

 

When you have an unnecessarily complex net, you run the risk of unpredictable results due to the compiler organizing the instruction differently than you might have expected.

[i need connect modbus TCP/IP]

Just to make sure it's clear: You have two choices when communicating with four other devices over Ethernet. You may either: 1) connect to all four simultaneously using four different sockets, or 2) connect to each device sequentially using a single socket, connecting and disconnecting each time you transfer data.

 

For #1 you will have separate ladder rungs with four Socket Initialization function blocks, four Configuration function blocks, four Connect function blocks, and four Read and/or Write function blocks.

 

For #2, you will only have one of each, but the IP address must be indirect (using 4 MIs). You must load the IP address into the MIs, execute the Configuration block, execute the Connect, do the Read/Write, then disconnect and repeat for each of the remaining three devices.

[Samba memory limitations]

Unitronics Support was able to answer my questions and I have finished my first project using the new Samba. Because we wanted to get a little experience with this PLC, we decided to use it for an in-house project we've been wanting to do. The Samba PLC will be controlling two air compressors and monitoring their operation to avoid problems we've had in the past with the compressor motors running until they burn up when some problem occurs such as belt loss or loss of pressure.

 

My problem was that I initially tried programming the PLC like a slimmed-down V570 (since it has a 320x240 color touchscreen, just like the V570) instead of like a souped-up Jazz. I was able to work around the memory limitations and ended up with a minimalist, but very functional controller. The program has 6 screens, including a Main informational screen, vital statistics screen, Log screen, a Configuration screen, a Password Login screen, and an Installation screen to allow ease of initial setup. The program monitors two analog pressure sensors and appropriately controls two compressors with alarms, notifications, and logging. It also includes programmable timers to allow operation only on weekdays and/or during normal working hours. I'm pleased with the result and also pleased with the new Samba.

[Samba memory limitations]

I'll do that, thanks.

[Visilogic Timers]

Thank you! You know, I think I knew that and was having a senior moment.

[Visilogic Timers]

I've been working with Unitronics PLCs for nearly 5 years and one thing has always frustrated me - all 3 timers decrement. When I want to have a simple display of elapsed time (e.g. the time a valve has been open or a pump has been running), there is no simple way that I can see to display that information without a lot of convoluted ladder logic. Have I been missing something all this time?

 

Experienced Visilogic programmers: surely you have this same need from time-to-time - how do you approach it?

[Samba memory limitations]

I'm currently working on a project that I thought would be ideal for the new Samba PLC. Unfortunately, I'm finding the memory to be shockingly limited and can't seem to easily work around it. This project has 13 screens (many of which are still empty since I've already exceeded the allowed PLC memory). When I run the "Projected Memory Map", I see that the vast majority of the memory is being taken up by "HMI Variables", but I can't get any information within that to tell me where the problem might be. Which "HMI Variables" are the most likely to use large amounts of memory? How can I find which elements are causing problems?

[Win7, too big fonts in VisiLogic, and windows problem]

Go to:

 

Control Panel

Appearance and Personalization

Fonts

Change Font Size

 

Be sure "Smaller - 100%" is selected.

 

If your Control Panel is set to display All Control Panel Items, then just go to Control Panel/Display and make the same selection.

[Show time on HMI]

Look on the toolbar to the left of the HMI editing screen. There you'll find a section labeled "RTC". The first item that looks like clock hands set to 3 o'clock is what you're looking for.

 

I put the day of week, date, and time on every HMI screen I build.

[Only copy part of a Data Table column to a vector?]

In that case, create another Data Table with a single column and only 100 rows. Send the data to this table also, shifting the entire table down one row prior to each entry. This will maintain the last 100 data points and allow you to read them out into 100 MIs when you want to do your range calculation.

[Only copy part of a Data Table column to a vector?]

Why not determine the range as you go? Simply check each new number to be greater than the last highest number or less than the last lowest number and if true store it for the next check.

[Latches Output]

You can also use a "Binary Text / Switch" and check the box for "Toggle". You can then use the ladder to Reset the bit or Output, if needed.

 

I like this method because the operator can "see" that the Output is on and can also turn it back off manually if necessary.

[Animation in HMI screens examples]

I don't know if it would apply to UniLogic, but with VisiLogic I use a bar graph that increments continuously from 0-10 on a 100ms pulse. The bar graph is sized and colored to simulate the liquid flowing in the pipe.

[Samba Snap-In I/O]

I have one more question. I was surprised to find that I couldn't change the HW configuration from a V570 project to the Samba since they seem to have the same HMI attributes. The error message said they had different capabilities (or something similar). Can someone briefly list the major limitations I should expect to encounter while programming a Samba versus what I'm used to with the V570? Thanks.

[Samba Snap-In I/O]

Thanks, Cara. I'm old and my eyes are not what they used to be.

[Samba Snap-In I/O]

Can someone tell me what is the basic difference between the T-20 and R-20 Snap-In module for the Samba? All the bullet points on the website are identical.

[Ethernet/IP]

However, we use Allen Bradley PLCs on all of our machines, so we are currently not able to communicate. We rely heavily on Ethernat/IP.

 I regularly use V570s and V1210s that must communicate with each other and customer SCADA systems and customer PLCs that are not Unitronics. I typically use MODBUS IP over Ethernet and it works very well.

[Data tables problem]

Good suggestion, thanks.

[Data tables problem]

I see what happened - the file was too big, but it was only 50K. Any idea why I'm limited to a 11.04KB file size on uploads? Almost anything reduced to that size is unusable.

 

I can't upload the applications without going back and re-creating the whole event and I really don't have time for that. The main issue is that VisiLogic refers to Data Table column internally by something other than the name of the column and there is no indication that is the case when the programmer is working with VisiLogic. If a Data Table is edited such that columns get re-positioned, but everything looks identical to the user, some functions will not work as expected (such as copying the Write Row to Data Table function block from another program with a seemingly identical Data Table.

[Data tables problem]

I ran across an interesting problem today. While I was able to figure it out and correct it fairly easily, I think it points to an underlying problem with how VisiLogic is dealing with Data Tables. Here is what happened:

 

I have a project I was modifying for another use. In it I have a Data Table with 3 columns. Part of the project modification involved editing column 3 and adding a column 4. In another project I had already made a similar modification and had some logic to write data to the modified Data Table, so I copied the logic from the second project to the first after modifying the Data Table in the first, but the Write Row to Data Table function block reversed the last two items. I confirmed that the Data Table in both projects had the exact same name, exact same number of columns, each column had the exact same name, and each column was of the exact same data type, but no matter what I did, copying the function block inexplicably reversed the last two items (NAME and EVENT columns in the attached picture).

 

The problem turned out to be that when I edited the Data Tables in the two different projects, I went about it very slightly differently. When I inserted a column in one of them I did "Insert Before" and in the other I did "Insert After". That had the result that Visilogic identified them internally as reversed and thus reversed the columns in the Write Row function block. There is no external indication that VisiLogic is using some other method to identify columns other than the column name, but it does. In my opinion, this is poor programming practice - if VisiLogic is going to identify the columns by something other than the assigned column name, then it needs to be indicated and that is the indicator that should be selected in the Write Row function block (labeled "Destination (Cell)".

[Visilogic 9.7 clone files corrupting graphics]

He's talking about the SD password, not the Info Mode password. In order to save a program file to the SD card from the PLC, you must have an SD Password function block in the program. The FB should be executed by the Power-up bit (SB2). With that FB in the program, SD files can be saved using the password assigned in that FB.