Flex727
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Posts posted by Flex727
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@Ausman is correct - you need a hub, not a switch (I misread @Joe Tauser's post), which I don't have. However, I did some other experiments. I increment a DW on every scan and divided the R/W Mix Acknowledgements count by the scan count. The result seemed to vary a bit from startup, ranging from 82% to 97%, but mostly hung around 95-96% and was remarkably stable there. The PLCs connect through a switch, along with my desktop PC. The rest of my network is wifi through a router and so the PLC network is independent of other devices. The scan time of the Master PLC (V1210) is 7ms and the Slave PLC (V700) is 3ms. Since these are nice prime numbers, I expected to see a lot of aliasing to cause dropped packets, but that doesn't seem to be the case.
With very consistent >95% communications success rate on every scan, I'd say the Unitronics PLC is indeed completing the entire MODBUS R/W Mix function in a single scan. I could see no effect even when online with the PLC using Ethernet (on a different Port & Socket, of course).
Many of my projects that involve MODBUS TCP communications are on an isolated network. When that is the case I plan to always execute the comm FB on every scan rather than try to run a timer to slow it down. It makes the Slave PLC as responsive (to button presses, etc) as being at the Master. I wish I had realized that you could communicate on every scan years ago.
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MBs are bits. Use them.
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You may be able to use the "Toggle Register Bit" function under the "Logic" ladder menu for this purpose. What are you trying to do? Typically in VisiLogic, bit vectors are employed to do this rather than trying to manipulate the bits in an integer register.
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Moved to correct forum.
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3 hours ago, Bowie said:
Do I have to have the PLC connected to a network to utilize?
To utilize what? Yes, you can always store data to the SD card and physically retrieve the card to access the data.
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I have Wireshark and an Ethernet switch. When I get a few moments I'm going to try that.
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I just completed a project and noticed something odd. The project is as follows:
Chemical blender controlled by a V1210 PLC. This machine blends 4 different chemicals to the customer's specification into 4 different tanks (each with a different mix of the 4 chemicals). The chemical flow is controlled by 4 Entegris flow controller/flow meters (analog I/O).
A remote panel (V700) is located 50ft. (of Ethernet cable) away. This remote panel can control the operation identical to the main panel. Blending and tank filling can be started or stopped at either location.
Communication between the two PLCs is by MODBUS TCP with the V1210 as the Master and the V700 as the Slave.
Since all blending operation and control occurs at the main (V1210) panel, but operation of the system will generally occur at the remote (V700) panel, I wanted the best user experience I could obtain at the remote panel. If you've ever had remote control via MODBUS, you've noticed that there can be a bit of a lag to get a button response on the HMI screen (i.e. you usually have to hold the button down for a short time to get it picked up by the MODBUS polling). I usually run polling by either a timer or use SB 15 (100ms transition). The shortest timer possible is 10ms, which improved things considerably, but I checked the scan time on the V1210 and saw it was between 6 & 7 ms, which might improve things further. I was using the Unitronics R/W MIX FB to transfer data and hung that directly on the left rail (with SB 150 and the "function in progress" bit, but no timer). This caused the data transfer on every scan and dramatically improved the user interface at the remote panel. It was nearly as responsive as the main panel. Checking the TXD / RXD counters, there were no dropped packets at all - very good result, and I'm quite happy.
However, I did notice a minor oddity. Also on every scan, I am performing the necessary integration of the flow rate to total volume and display it on the screen. My normal method of integration in this type of circumstance is to time slice the rate using SB15, perform the necessary math to convert mL/min to mL/100ms, then sum to obtain total mL. On the main panel where all the calculations are performed you can see the flow rate is constant and the total volume increments up very smoothly. However, on the remote panel where that number is transferred over on every PLC scan (of the V1210), the total volume does not increase smoothly. It has a halting appearance, not smooth at all, that totally mystified me for awhile.
I think I now know why (though I could be wrong). Anyone want to take a stab at solving this mystery?
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I'll PM you.
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If you have VisiLogic installed, you can attempt to upload the project from the PLC. The chances are slim that you will be successful, as the programmer must take an extra step to allow that - the default is to not allow upload.
Without the original .vlp file you may not be able to proceed further without some documentation. If you have some understanding of how the machine works and how it is wired, someone may be able to re-create the program for you.
Hopefully I've overlooked something and someone will be able to chime in and offer some additional help.
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I presume you do not have the original software file (.vlp) that the PLC was programmed with? What is the PLC model?
I'll tag @Maurice118 for you on the off chance he's the guy you're looking for.
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Does it occur with only one project or with every project you open? If every project, I would completely uninstall VisiLogic and try again. If only the single project, then I would send the project to Unitronics support to see if they can fix it.
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Moved to the correct forum.
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Did you try actually measuring the current with multimeter?
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If you don't see I 0 on when you go online with the PLC then you have a wiring problem with your input. If a Set coil latches, then it means the input flickered on so rapidly that you couldn't see it.
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Did you go online with the PLC and see that I 0 and O 0 were energized when the input signal is on?
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If this isn't working for you (see attached), then post your code.
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This doesn't appear to have anything to do with Unitronics products. If it does, please respond with more info. Otherwise I will delete the post shortly.
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Is this Vision or UniStream?
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I've seen power spikes or glitches change timer values. If you keep having the problem due to some electrical interference, you might try loading the timer preset into an ML and storing it back at the appropriate time.
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You have your laptop set to the same IP address as the PLC. That won't work.
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Maybe I wasn't clear. If you want help, you need to address every item that DanT mentioned - not just the last one.
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It would be helpful if you addressed the troubleshooting comments when you respond. No one can help you if we don't know your situation.
@DanT was kind enough to type all this out. Please let us know that you've gone through each of these on the other laptop that you're now having a problem with.
On 12/5/2019 at 10:19 AM, DanT said:Is the Ethernet Cable Plugged into the Ethernet Port ? and are the LED's Flashing for connectivity?
The Expansion port uses a RJ45 Connector also, and is often confused with the Ethernet port.
Check the PLC using INFO Mode ( Password 1111)
Ethernet
Upper lines show Ethernet IP and current status
Middle allows you to view and set parameters - IP, Sockets
Press Monitor to see if any data is reaching the PLC ( selectable by the port )
Are the PLC and PC on the same network? Check the address of the PC.
Can you PING the PLC IP Address from the PC and get a reply?
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Are you using the same computer for both VisiLogic and Remote Operator? If so, they would be using the exact same pathway and if one works, the other should too, but they both can't connect to the same port at the same time.
If not, then make sure the Remote Operator computer (or phone) is on the same subnet as the PLC. What I find is that my router hands out addresses to wired and wireless (wi-fi) with different subnets.
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1 hour ago, t0r3r0s said:
I have one more problem I cant connect to my remote operator .
Did you fix the problem with MB 102?
Storing bit into DW with offset
in Vision & Samba PLC + HMI Controllers & VisiLogic Software
Posted
Very nice, @John_R! This is the best answer, IMO.