Setpoint rate limit is not applied on 3216 controller

The setpoint rate limit does not seem to work on a 3126 controller I am working with. I tried it in both OPC iTools and also from the supplied Labview VIs. I can enter a setpoint rate limit, however when I enter a new setpoint, the working setpoint immedeately goes to the value of the target setpoint, so no ramping is done. I have done this previously on other devices with no problems regarding that.
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  • Could you send a clone to tim.linnell@invensys.com please?

    There are some circumstances where the ramp limit is not applied, which from memory (I wrote the firmware) are mostly around use of the setpoint programmer. But given a clone file it should be fairly easy to figure it out.
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  • Thanks for the clone file,

    The ramp limit doesn't operate when the setpoint programmer is engaged because the programmer is mastering the ramps to create a profile. From memory, if the program is in an "end" state at the end of a sequence, the ramp won't operate, it needs to actually be in the "reset" state which is entered using a mode key sequence. This is probably what's happening in your installation.

    I haven't got an instrument to try this on - actually at home today - but will pass back to the office or look on Monday. Or you can try on the instrument/itools by setting the program status to reset in which case let me know what happens!
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  • Hi Tim,

    thank you very much for your quick reply. I tried setting the Programmer to "Reset" mode, but still the behavior is the same. It would be great if you could look at this on an instrument.

    Thanks again!
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  • Thanks David, I'll get something set up and get back to you shortly.
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  • Hi, David and Tim

    David please check and verify your 3216 is a controller and not a programmer i.e. the Timer Type is not set as PROG(10) .

    My understanding is that when the 3216 has the programmer option enabled i.e. the Timer type is PROG(10) then the instrument expects the Ramps to be controlled by the Programmer segment ramp rates and not by the Setpoint Rate limit. This is why, even with the programmer in reset, when you enter a setpoint rate limit value, it is ignored and the working setpoint goes to the value of the target setpoint.

    If you change the Timer Type to None(0) then the Working setpoint will ramp to the target setpoint using the Ramp Rate limit value.

    I hope you find this information helpful
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  • Hi Dimitris,

    Thanks for your help, I think what we have here is a programmer, hence its behaviour.

    I cannot find the Timer Type function anywhere, neither in the iTools, nor on the front panel. I flipped through the manual and it tried to access the timer function from there (set it to Level 2), but to no avail. Does this mean a device configured as a programmer CAN NOT be used as a timer? That would be rather inconvenient...
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  • Hi David,

    If the 3216 you have is a standard controller with the additional Programmer option, then you should have both the programmer and the timer options.

    Since you are familiar with iTools please try the following:

    Connect to the device using iTools, place the instrument in configuration level and click the Views button. Under the Browse tab, select or double click the Timer Folder. This will bring up the Timer parameters.

    The first parameter named “Type” has all the options available for selection. If it is set to PROG(10) then the instrument is a programmer only. Change it to any of the other options except None(0) to use the timer.

    See attached image.
    I hope this helps.
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  • Hi Dimitris,

    Thanks for your quick help. But even when I set the device into configuration mode, I do not have the folder "Timer" in the Parameter Explorer. Is it possible that this device has been shipped as a Programmer _only_? How could I check that?

    thank
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  • Hi David,

    I have checked the clone file you have provided to us and the instrument you have is a Programmer Only. It is a carbolite special with firmware A2.62

    You can verify this for yourself. If you can, please turn the power Off and On again to the device. During start-up the 3216 will display the Firmware version. In your case it will display A2.62

    If the 3216 was a Standard controller, the firmware would start with the letter V

    I hope this explains why you cannot see and set the timer
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  • Hm, this explains a lot. So, is there any way I could update the firmware? I have to say I find it a bit strange that Carbolite strips the controller of some of its basic functions...
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  • Unfortunately we can't update the firmware on Carbolite equipment under the terms of our supply agreement with them. The Carbolite variant of the 3200 controller was specified by them as a ramp/dwell programmer running a fixed sequence, and operation was optimised around the function needed. Obviously if we were to change the firmware it would have implications for the operation of their equipment and warranty/safety etc.

    I'll bring this conversation to the attention of Carbolite and see if there's anything that can be done.But it may be simplest to use the programmer function to do the ramping rather than the rate limit function.
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