Flex727
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Posts posted by Flex727
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This is very simple - just use the ASCII String Variable for input and display. It allows input as ASCII text and stores the data in a MI vector (2 charactors per MI).
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Thanks also, linxchas. I have used UDP Raw before successfully, but have been hesitant to use it when the PLC is attached to a customer network. MODBUS UDP sounds like it would be useful to me in this situation because of the speed and simplicity. Should I infer that it will coexist harmoniously with a standard TCP/IP intranet as long as I keep the polling rate to about 100ms or so?
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Thank you, Damian. That's actually a bit quicker cycle than I thought. I had assumed there was no way to complete the survey of all 15 slaves in less than 2 sec, even using multiple sockets. I also may not have to write to the slaves (not sure yet). I assume if I only need to read a vector of several contiguous MIs from each slave that this will also speed things up?
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I have a project that I'm working on where I will need to communicate with about 15 slaves. I will be using a V570 for all 16 PLCs and communication must take place over Ethernet, but protocol is at my discretion.
Can someone suggest the best way to accomplish this? It would be nice to complete the survey of all 15 slaves within a second or two, if possible, however, I'm thinking opening and closing sockets, four at a time, may take longer than that with MODBUS IP. I would, though, prefer to use MODBUS IP unless there is a protocol that dramatically improves this communication situation.
Thanks for your help.
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Take a look at the example project called V280_Ethernet_TCP_MODBUS_IP_Master.vlp, specifially ladder rungs 3-6. Note that you need to set a bit for Read and Write requests and then use a Direct Contact for the R.H.R & P.H.R functions with a Reset of the bit after. Note the inverted contact for Function in Progress in series.
What this does is allow the request to remain open until the Function in Progress clears and then the Read or Write will occur.
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Thanks, Gabriel, I didn't think of that. I'll check it out.
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No, I want the USER to be able to toggle a bit. On the V570, the HMI element "Binary Text" has a checkbox labeled "Toggle" that when checked will toggle the linked bit when the user touches the Binary Text element. I am looking for that kind of functionality on the V130. I recognize that I can place text on the screen that says "Press #1 to toggle X" and "Press #2 to toggle Y", etc, but that is clunky. I was looking for something that would allow a user to "highlight" some element on the HMI screen and press a key to toggle a linked bit, then move to the next element and press the SAME key to toggle that next bit, and so on. I recognize that there would be some underlying code to make all that happen. This all not unlike the regular HMI numeric or string entry elements where the field is highlighted, the user presses "Enter" to make that element ACTIVE, then updates the variable. That's what I want for bits - fields on the screen that the user makes active and then toggles the underlying bit by pressing a key.
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I normally work with the V570 PLC, but I have a project I'm working on right now using a V130. A common element in my V570 projects is a bit toggle where the user touches the "Binary Text/Switch" on screen to toggle a bit in the ladder. Is there something equivalent for the V130? I know I can create a keypad entry to enter a "1" or "0" and convert that to a bit, or I can place a message on the screen to press a specific key to toggle the bit, but I will have several of these on screen simultaneously. Ideally, I would like the user to "highlight" some text on the screen and press a key to toggle that text, then cursor over to the next entry and press the same key to toggle that next entry, etc. Is there any way to do this?
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Just to keep you occupied until the resident geniuses drop by, take a look at the example projects available under the Help menu. Go to Help/Examples/Project Examples/Communications/Ethernet/Ethernet MODBUS IP for an example each for Master and Slave. The examples are for a v280, but it's the same for all the Vision PLCs.
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Hi,
At the moment there is no such a simulator available, and checking applications require an actual PLC.
We are aware of the need of a simulator and planning on issuing one in the future.
Initial response: Yay! They're finally working on one!
Second look: Oh, that reply was posted almost 2 years ago.
I'm really surprised this is turning out to be so difficult.
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Outstanding explanation, Damian! I have been tripped up by that before and never really thoroughly understood what was happening. Very helpful post.
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Joe, that was a great example - thank you for posting the example program. Just one more question: how do you normally handle placing the machine into the initial idle state (MI0 = 10)? Would you normally set the "Power-Up Value" to 10 or use some logic to pre-determine which state the machine should start up in?
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Thanks for the helpful suggestions. Here is what I ended up with for the "Master" PLC. Perhaps this is a bit unwieldy, but it seems to work well. I broke the comm error up into two parts. If the Socket (3) isn't initialized, I re-initialize the ethernet card and socket then try to connect the socket. If the socket is initialized, but not connected, then I skip the initialization step and just try to reconnect the socket. For each, I re-attempt every 2 seconds. This seems to handle the varying circumstances well - if both PLCs are connected to a hub or switch, then where the loss of communications occurs results in different situations. The MB125 "Comm Error" bit is the same logic as I showed in my initial post, above.
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I swear every time Joe Tauser makes a comment on this forum I learn something. Joe, can I trouble you to elaborate a bit on what you mean by "I use a pointer register and equal blocks to jump between states and the subroutine is always called when the state machine is not idle; this way the coils will get written properly and not be left on when I leave the subroutine"? I think I understand the first part - each state has a number associated with it and you call the subroutine when the state equals a specific number, but I don't understand what you mean by "the subroutine is always called when the state machine is not idle; this way the coils will get written properly and not be left on when I leave the subroutine". Also, what is included, generally, in the "beginning 'idle' state"?
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I'm sure someone more authoritative will come along, but in my experience, any coil in a subroutine that is not executed will remain in the state it was in when the subroutine was last called. This is similar to and would be the same for any operand in the PLC that has no coil associated with it at all (i.e. remnants from a previous program) - they will always remain in the state they are in until a ladder rung with that coil is explicitly executed. This is why it can be important to initialize the PLC when loading a new program.
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Excuse me for bumping this topic, but I was hoping there would be somebody out there with some experience to share. Thanks.
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I wonder if any wise programmers might have some helpful hints. I've been programming for awhile, but I'm still a bit sketchy about networking. When I have two v570 PLCs communicating with each other, it's important to know (and potentially correct automatically) when a communications error occurs. I'm attaching a subroutine example in the master PLC where I communicate with the slave and detect a comm error by looking for a change in the count of data received to the socket (SDW21, for Socket 3) - ladder rungs 5-7. Currently I initiate communication every 250ms and if I go for 2 sec without the RXD count increasing then I alarm. This seems to work well, but is there a better way?
Also, when a comm error is detected, what is the best procedure for making an attempt to re-establish communication automatically?
Thanks.
By the way, I'm using VisiLogic 9.4.0, if it matters, and communicating by MODBUS IP over Ethernet.
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Thanks, I should've mentioned that I'm using a v570.
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Is there any way to create a slider bar on the HMI that would control an MI smoothly between two values? An example might be to control the screen brightness by varying SI9 between 0 and 100 with the slider controlling the value.
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Thanks, Cara. I had that set up on my previous laptop, but haven't set it up on my new one yet. My recollection (which may be faulty) was that I couldn't copy and paste between separate instances of Visilogic, but had to open a project, copy the elements (either HMI or ladder), open a new project (which closes the previous one, of course), then paste it in. That works, but is extremely cumbersome.
It seems like I've heard about a simulator being "in progress" for a couple of years now. Is it really - or has it been dropped?
The v570 PLC HMI with only 320x240 resolution is so far behind the times that it's very difficult to explain to a customer. At that resolution the interface always looks much less professional than it could be and complex screens are often impossible to produce correctly. This leads to a much more clunky interface by having to break screens up in a way that is not always logical or representative of the equipment being controlled. I strongly recommend that Unitronics take a look at developing a 5.7" 640x480 product. Since Visilogic already handles the 640x480 10.4" product, I can't imagine this would be a very significant engineering undertaking. I'm sure it's more of a marketing question and if your research says there's insufficient demand for such a product, then that's a legitimate answer.
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It would be helpful to mention what operating system you're using, what brand of USB-to-serial converter you're using and what version of Visilogic you're using. However, the most likely culprit is the USB-to-serial converter. Unitronics has some specific recommendations that you can find elsewhere on this forum. I am currently using a Trendnet TU-S9 with my Win7 laptop and it's working very well and reliably.
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I've been using and programming Unitronics PLCs for several years now and I have to say that I absolutely love them. I always recommend them to my customers whenever I have the opportunity. However, there have been a few missing pieces that every user really needs and wants. I know this has been asked many times before, but it's been awhile so can a representative from Unitronics provide a quick update on the status of these issues? I realize it may not be possible to get too specific, but a simple "we're working on it" or "there are no plans at this time" or "we're working on it and we should have something really soon!" for each item would be great to see.
-PLC simulator built into Visilogic
-Online editing capability
-Ability to open more than one project at a time and directly copy and paste between projects.
-Ability to see both ladder logic and HMI screen simultaneously in Visilogic.
Also, is there any plan to introduce a 5.7" format PLC with a 640x480 screen resolution? The limitations of a 320x240 screen are sometimes extremely difficult and my customers do not have room for the larger format (10.4") PLCs. Most of your competitor's HMI screens that are similar size as the 570 are 640x480.
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It does seem odd that the default on a laptop would be 125%.
I would be very interested to know if this affects the delay time.
My laptop is an HP - maybe it's an HP thang.
By the way, Cara, I think changing the Windows font setting to 100% from the default 125% seems to have also solved the problem I was seeing with delays during HMI editing.
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Cara, once a program is loaded into a new PLC I never see the splash screen again - should I? However, I didn't realize it was so easy to change - thanks for the info.
Emil had what I was looking for and that worked perfectly. Thanks! (to both of you)
Timer Preset Behavior
in Vision & Samba PLC + HMI Controllers & VisiLogic Software
Posted
I wonder if someone from Unitronics, or some other knowledgeable person could provide a detailed explanation of how Timer Presets behave. With Timers, there is an extra option besides just "Power Up" value being set or not set. I can enter a Timer Preset in Visilogic without checking the box for the "Power Up" value and that Preset gets transmitted to the PLC during program load. If I subsequently change that Preset, either in Visilogic or in the PLC, then there will be a dialog box requiring me to harmonize them if I do another program download. However, if I load the same program via the SD card I get different behavior. It appears to me that the Timer Preset in the program on the SD card (either .v57 or .c57 file) is ignored when downloaded. I would think, especially when I'm downloading a Clone program, that the resulting PLC would be identical to the PLC that uploaded the file. This is not the case with respect to Timer Presets.
What is the behavior I should expect? And is it any different if I have checked the "Power Up" box in the programming?