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  1. #1
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    LGR250-DDC01 VAV Heat/ Cool Write Access Denied

    Hi All,
    I'm new to this forum. I'm having difficulty writing properties to my BMS. We have an Automated Logic BacNet LGR250-DDC01 and the WebCTRL BMS software. I'm trying to use a BacNet Discovery Tool and "write" values to "Heat Request" and "Cool Request" objects. I'm getting write access denied error. I'm not sure why this is happening and I'm not sure how to fix this so that I can write from the BacNet discovery tool. Any help will be much appreciated.

  2. #2
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    Jul 2016
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    Orlando, FL
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    Cool

    Hi there,

    There is a simpler way to accomplish the mapping of heat and cool requests to parent equipment.

    1. Open the logic for the parent equipment (i.e. Air Handler, Chiller)

    2. Click the request microblocks per type you want to assign.

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    3. Click the "Details" tab in the new window.

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    4. Click "Add" to add a new mapping point

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    5. In the Geo window showing the site, find the box you wish to assign, and click the arrow next to that boxes' program, and find the Heat or Cooling Request point and click that point.

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    6. Begin again from Step #4 and repeat. *10 boxes can be assigned per Request microblock*

    7. Hit Apply when done, and see the points come in, if they error, you will need to check the microblocks in each program and make sure they are "Network Visible".

    I can assist with the Network Visible part too if need be.


    Hope this helps you out!

  3. Likes sriram155 liked this post
  4. #3
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    Jul 2016
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    Hi ThePraetorian,

    Thanks for the reply post. I tried adding based on your instructions however, I dont' see the option to add. Please see snapshots below.
    (Refer Image 1)
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    Let me try to explain what I'm planning to do here. I've a VAV in a room called "Phone Lounge". I want to control the temperaure in this room by doing any one of the following:
    1) Vary the damper position (Refer Image3, Image5)
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    2) Heat/ Cool request (Refer Image 2)
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    3) Vary the temperature setpoint (Refer Image 3)
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    I intend to do this via a PC connected to the same network that has a Bacnet explorer software something like ccontrols bacnet discovery tool.

    When I try to send a "Write" request to the Analog Value Object Property cool_request_1, the properties are not being updated on my BMS. I get error saying write access denied. So I went ahead and tried giving Admin access to Anonymous user (just to try if this solves my issue 0f write access), and still I'm unable to "Write" values via Bacnet explorer software to my BMS.
    (REFER IMAGE 7, IMAGE 9)
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    What am i doing wrong? Why am I unable to "Write" values in to the BMS from another software when I'm clearly within the same network, I've granted full access to Anonymous user.

    Here are few more settings screenshot for reference.
    (REFER IMAGE 4, IMAGE 6, IMAGE 8)
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    Any help would be much appreciated.

    Ram.

  5. #4
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    Gotcha, it appears you are going to the AV microblock for heat/cool requests in the VAV programming. You will need to find the programming for the associated air handler unit that provides conditioned air to the VAVs in question. In that Air Handler program you should see the request blocks there. Those are the blocks you will need to open in order to associate the requests to the unit. The blocks you appear to be opening are the "Output" if you will, they send the requests out, but you need to complete the mapping on the air handler program in order for it to do anything with the already generated requests.

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  6. #5
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    I saw also, that you seem to be attempting to change the control sequence for the "Phone Lounge". You stated that you, "want to control the temperaure in this room by doing any one of the following:
    1) Vary the damper position, 2) Heat/ Cool request, 3) Vary the temperature setpoint"

    Can you give me more of a breakdown of what changes you would like to see based on temperature change or deviation from setpoint?

  7. #6
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    Hi ThePraetorian,
    What I'm trying to achieve could be a simple task. I'm not sure if I'm explaining well. I'm creating a simple web app with 2 buttons (Warmer, Cooler) for the occupant to request to make the room hot or cool. The function is pretty similar to the RS Pro's warmer & cooler (shown below). I'm not sure which of my object (temperature setpoint or damper position or heat/ cool request) should I write to, to achieve a similar functionality via the web app I'm working on.

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  8. #7
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    Ok, I am beginning to see what you are attempting, but I have a few more questions;

    - How is the occupant going to access the "Warmer / Cooler" buttons? Do they have WebCTRL access?

    - Is there a way to change out the zone sensor to an RS or ZS sensor? That way they would have actual local adjustment ability.

    - You could make a simple logic change, using parameter adjustments tied into the Setpoint microblock, all being adjusted from the graphic page, but you WOULD have to make a programming change.

  9. #8
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    Quote Originally Posted by ThePraetorian View Post
    Ok, I am beginning to see what you are attempting, but I have a few more questions;

    - How is the occupant going to access the "Warmer / Cooler" buttons? Do they have WebCTRL access?

    - Is there a way to change out the zone sensor to an RS or ZS sensor? That way they would have actual local adjustment ability.

    - You could make a simple logic change, using parameter adjustments tied into the Setpoint microblock, all being adjusted from the graphic page, but you WOULD have to make a programming change.
    - The occupant will have access to the Cooler/ Warmer buttons via a simple webapp using BACnet stack.

    - Zone sensor has only thermostat types as well as incremental input -1 0 +1. I've tried setting this option and immediately my room temperature drop from 24 degree to -1 degree. Local access via hardware like RS is out of the question. We need some form of web access other than the WebCTRL.

    - I'm not sure what type of programming change you are talking about. Could you please elaborate on it?

  10. #9
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    Jul 2016
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    Here is the Zone Temp AV block with available options. Presently, it is set to Thermisor, Precon Type II, 10k@25 deg C. I've tried changing it to Setpoint adjust switch -1 0 +1 and immediately, the room temp drops to -1 deg.
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  11. #10
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    Quote Originally Posted by sriram155 View Post
    - The occupant will have access to the Cooler/ Warmer buttons via a simple webapp using BACnet stack.

    - Zone sensor has only thermostat types as well as incremental input -1 0 +1. I've tried setting this option and immediately my room temperature drop from 24 degree to -1 degree. Local access via hardware like RS is out of the question. We need some form of web access other than the WebCTRL.

    - I'm not sure what type of programming change you are talking about. Could you please elaborate on it?
    Not sure if I understand the occupant access over webapp, you could simply get a RS sensor and run a four conductor and give them local and easy access to adjust the setpoint...OR
    there would need to be a programming change to your logic in order to provide an adjustable setpoint.

    Can you attach program and view file? I can make a quick addition and give this to you.

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