Emil
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Posts posted by Emil
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Hi Flex,
I'll try ot answer your questions:
PV range (Low and High limits) is the range PID operates and makes its calculations. Then, Proportional band (Pb) is defined as percent of PV range (with resolution of 0.1%). Proportional error Ep is calculated as percent of Pb. Ep is 100% at the border of Pb and 0% at SP.
As PV range is wider, as the absolute error in stable state is greater - having the same error in pecents. In other hand, making PV range too narrow, you risk to exit this range and then PID will be messed.
For example - if you want to heat water up to 60-80 C and you use PT100, which hardware range is -50 to 460C (IO-PT4), you can set this range as PV Min/PV Max. This is not a "mistake", but, having in mind that the water temperature usually doesn't exit 100C (boiling water) and 0C (ice), if you will set this range > 0-1000 (100.0C), you will have significant more precise PID control.
Where yo want to perform Autotune - in the congtroller itself or via PID server?
Based on my experience, I'll not perform Autotune in pressure keeping system.
I'll recommend to start with Pb = 1000, Ti = 500 and Td = 50.
BTW - setting Ti and Td = 0 disables respectivelly integral and derivative control.
Please take log with PID server and send it to support@unitronics.com.
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Hi,
Of course there is Negative transition contacts in Jazz and M91.
Each button has Sistem Bit (SB) linked.
To perfomr operation wne one release the button, as Tim stated, you need just to make condition -> Negative contact of related SB... If you want this to happen only on specific display, you can add to the condition compare SI2 to relevanr HMI.
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Short answers:
1. you need ot use High Speed Counter of the controller itself. You can set it to High speed countert (HSO) only or to Encoder. See hardware configuration of your project for details.
2. FB PID offers full PID control. PI is partial option - Td = 0. In my point of view, it depends on your system, but te tool is the same.
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Hi Damian,
White is always a mix of several wavelengths. This is phisics! If the spectr of white LEDs is diferent from the spectr of flourecsent lamps - I don't know. If I'll try to contact producer and find the spectrum, will this help?
BTW - you can control backlight intensity in steps from 0 to 100.
If the photo material is sensitive to some colors, you can make HMI, avoiding these colors. This sounds to me better soluion than B/W. I remember the old dark rooms had red ligths. So maybe you can design the display in variations of red?
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Hey Morten,
You can set initial Ethernet parameters from Info mode and this way you can contact from, let's say VisiLogic and operate (download to, for example) totaly new controller.
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Hello,
We made similar tests here with modem/router Sierra Wireless Raven EX. It was programmed via Internet and receives its IP, which then we use as gateway.
In the other side there needs ot be ordinary PC connected ot Internet.
In our tests we loaded all 4 sockets at the same time - Web server, connection to VisiLogic, Connection to Remote operator and running Modbus. The connection was very stable and data transfer - very fast! We connected from 4 different PC.
Why you need to use GPRS modem on PC side?
What is the connection between PC and modem - Ethernet or RS232?
Are you sure the controller has access to Internet (public IP)?
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Hi Vadimas,
M-Bus is not an option.
What you can do with RS232. What is the protocol behind this port?
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Hi Ron,
You need ot count from LSB (right). For example, if in ther register (MI, ML, DW...) you have value "1", this means that bit with offset 0 and only bit with offset 0 is active.
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About execution time - there is simple, practical and elegant solution - functin "Interval". It lets you to measure versy precise execution time from point to point in your application.
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Hi RedLotus,
Please take a look on example Keypad Entry Force cursor (U90Ladder > Help menu > Sample U90... > Basic HMI operations). I have strong impression this is what you're searching for.
Please let me know if I'm right.
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Numeric keyboard was not changed. ASCII (alpha-numeric) was totaly redesigned and now is very attractive!
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Hi Martin,
In 4-20 mA signal, as low is the impedance, as better. Usually, when you need to disable 4-20 mA analog signal, you need to short circuit it (0 Ohm load).
In all specs I saw in my life, it's stated "max permitted load" of the sensor/transducer. Are you sure in your case it's "exactly 250 ohm"? This is very strange. Can you send the spec of this transducer to support@unitronics.com?
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The best option is to contact our distributor in South Africa. They have experience...
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Hi Ray,
Currently Unitronics doesnt' support EtherCAT.
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No! Only some very old unts, produced about 8 - 9 years ago...
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Small note - after 3 unsuccessful tries the upload is blocked - this is true. But if you restart the controller - power OFF and then ON again), it's open for another 3 tries.
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Hi,
Attached is a scheme to connect potentiometer to AI.
It "kosher" - it means it's generated bu our R&D and is checked here.
FYI.
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Hi,
SB90 is "pure" for internal use in Unitroncs laboratory. There is no way ot use it in the field. That's why it has no description.
If you have any problem, please describe it and we will find a way to help!
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Please, when on line, press the buttons one by one and check relevant SB and SI6 value. This will let you understand if the problem is in software or in hardware.
If it's in hardware - how old is the controller? In which conditions it was?
If SI6 reacts properly to all butons, there needs ot be problem in user application. You can find them practically in On Line mode, searching where the button appears in the application and then check which other condition prevents the execution.
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There is not such built in function. It's quite rare request and I don't beleive we will make it. More over - it's relativelly easy to make it in Ladder with existing tools.
It seems easier to perform DT - Read column and save the values in vectors. Then you can compare (Vector compare - Vector menu) both vectors.
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Hi, as much as I remember, FDT is read-only which means that the values cannot be edited.
You can use Ladder to save the tables into UDT which is editable.
Furthermore, you can use the Unitronics.DataTables.DLL to read the whole structures and values and then save it into FDT, UDT or XML without using SD.
You can also implement your own function that will take the tables and will save it as CSV (it's really not hard).
Then take the data back and put it inside the tables (After reading the structure from the PLC) and update the PLC with the new values if needed.
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3G modems we know are quite different from the GPRS modems we support now. We tested here Raven EX from Sierra Wireless. It finds automatically the best way the cell provider offers for data transfer. It's very fast and stable. It has Ethernet interface so - in fact there is nothing to support from our side. You need ot program port forward in the device itself and then it acts as usual Ethernet gateway/routher. It's really great - nothing to compare with todays' GSM modems with RS232 interface. The only problem is the price. Sierra Wireless promises to output something simpler (yet same functionality from our side, but on half price. Let's hope soon...
Do you have in mine any specific devices you wissh we will support?
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Hi David,
SD card is divided to "chunks" of 512 bytes and each write is to such chunk. If you want to make your log more "memory effective", you can define a vector of 256 MI and then add each new record to this vector. When the vector is filled as close as possible to 509 bytes (the system needs 2-3 bytes for its purposes!) you will copy it as one delimited line to Excel. As each real line has its own <CR><LF>, when opening the file in Excel you will not feel in any way the result of "compressing".
If you need more help with performing this idea, let me know.
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About Force - in Vision series OPLC it exists! ... via Info mode or On Line!
Need PID help
in Vision & Samba PLC + HMI Controllers & VisiLogic Software
Posted
Hi Flex,
System like yours usually are very fast. When you prefomr Autotune, it in facts makes few ON-OFF cycles. This means, that the pump will be activated in full speed. This will lead to practically immediate overpressure - which will stop the pump.
It seems this is the situation in your case. When you start he pump, you're below Pb and the system activates the pump in full speed. This leads to practically immediate strong overshoot - probably above Pb. Result - stop the pump...
Is this what you observe and describe?
If you paid attention, I recomended you Pb = 100% (1000). This means, that in the moment you start the system the pump will decrease its spead practically immediatelly. Maybe even this will not be enough and you will need ot set Pb > 1000. This is fully legal. The result will be, trhat even on 0 pressure the pump will start with part of its max speed. As result, it will take more time to reach the setpoint (let's say 5 - 20 sec) and PID will be able to take full controll of your system.
I hope this info wilol help you to start te control.
Please try again PID server. It's very helpful. In case you need my further help, it will be very useful for me.