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  1. #1
    Join Date
    Apr 2005
    Posts
    72
    I need to control 24 induction unit chilled water control valves, each with its own temperature sensor (i.e. 24 control loops, temperature input, chilled water valve output)

    Is it feasible to have 'device' level network, where each sensor communicates to its related valve? (I realise one of the devices would need to do some logic/math regarding occupancy and %cooling required, so it is technically the controller)

    I assume this is possible with a Lonworks system, but is it practical?

    Any comments appreciated.

  2. #2
    Join Date
    Jul 2002
    Location
    Alpharetta, GA
    Posts
    168
    Sure!

    You can use one Lon controller and remote I/Os to control the valves. Your sensors can either be wired to the remote I/Os or be nodes on the network. I think a Lon solution would be perfect for this.

    I have only worked with TAC Xenta Lon controllers. From that manufacturer you would want the 400 series controller, 400 series remote I/Os with analog inputs and whatever type of output for the valves. If zone sensors are on the network, m/# STR 350.

    You could even integrate control of the window shades etc. - and of course serve up graphic pages on the customers ethernet or internet.





  3. #3
    Join Date
    Mar 2005
    Location
    Pacific Time Zone
    Posts
    4,192
    I second Freeze Stat. You would want a Xenta 401 as your central plant controller - (supports up to 10 I/O modules).
    You could go with 3 - 471's (8 UI's each) and 3-491/492's (8 AO's each) for a modulating 0/2-10VDC or 4-20mA Valve.

    You could also go strictly lon as in have not only the stats but the valve actuators that are lon stamped as well. Then you only have to run a pair of conductors to everything, or depending on what is in the building and what would be allowed you could get on existing wiring with convertors.

    The biggest feasibility that I see to going all lon (as in lon marked actuators, stats and programmable control(s) is if one item goes down it won't cause a bunch to go down. If a valve or a sensor dies (assuming one valve per stat) then only that part of the system is down vs. using a central plant controller that controls 8 valves. If that controller goes down then all eight valves are down. The other thing is wiring. If you went with an I/O module as mentioned above then 8 of your AI's would all have to come back to that one controller. Then 8 AO's to from the other controller to each valve.

    With all that being said it will probably cost you more upfront to go all lon stamped/marked/approved but you may cut some costs with labor (wiring) and the other factor being how critical the application is. To me going all lonmarked/stamped would be great but many customers don't want to pay for that added cost.

    I am sure (and hope) LonBoy will jump in on this and enlighten us all. ;o)
    "How it can be considered "Open" is beyond me. Calling it "voyeur-ed" would be more accurate." pka LeroyMac, SkyIsBlue, fka Freddy-B, Mongo, IndyBlue
    BIG Government = More Dependents
    "Any 'standard' would be great if it didn't get bastardised by corporate self interest." MatrixTransform
    http://threedevilskennel.com/ - not my website.
    Versatile Hunting Dog Federation - www.vhdf.org/


  4. #4
    Join Date
    Nov 2004
    Posts
    226
    Dont you need TAC's programming tool, or are these LNS based devices? Where would one buy the TAC devices from a distributor? Will they also provide the plug-in? Thanks.

  5. #5
    Join Date
    Apr 2005
    Posts
    104
    The configurable Circon SCC300GPC can control up three (3) control loops (2 Analog/1 Floating, OR 3 Floating), and can be found at Engenuity.com. Configurable, easy to use, ...

  6. #6
    Join Date
    Jul 2002
    Location
    Alpharetta, GA
    Posts
    168
    Originally posted by jimmyj
    Dont you need TAC's programming tool, or are these LNS based devices? Where would one buy the TAC devices from a distributor? Will they also provide the plug-in? Thanks.
    jj, you would need the Menta programming tool for the 401.

    Xenta products can be purchased through a local dealer. I was only using the Xenta 400 series to illustrate my point. If this was the only Lon project integrationx was going to be involved in it wouldn't be worth investing a lot of $$$ in software. If he felt he wanted to jump in with with both feet there are a lot of options.

    Also, we don't really know enough about the project integrationx was describing. For example, if this were a four-story building, I might use a controller for each floor in conjunction with a central plant controller. He will need to engineer this project based on a lot of factors we just don't know.

  7. #7
    Join Date
    Sep 2004
    Location
    SoCal
    Posts
    446
    OK Crabster, I'll toss in my 2 cents,
    Dude's Circon solution will definitely work - all iX-man will need is 8 controllers, 24 temp sensors, and of course 24 CHWV's that can be driven by the Circon devices.

    You could also use 24 LON CHWV's and 24 LON Temp sensors as long as either the sensor or the actuator includes a PID (perplexing, intimidating, difficult) control loop. Honeywell has one M7410G but may not be available in the US and I'm not sure if it has a plug-in. There's also quite a few LON temp sensors out there and you can check with Engenuity.

    Whenever selecting devices remember that the main thing to look for besides control functionality is LonMark certification and a free LNS configuration plug-in.

    Hey Crab, are you going to the convention? Any other of you control freaks attending? We could have our own crab feast at Scooters!

    Cheers,
    lb

    A hundred million nodes - it's a LON story.

  8. #8
    Join Date
    Jul 2002
    Location
    Alpharetta, GA
    Posts
    168
    lb,

    Dude's Circon solution would use 12 controllers if he wanted true analog output for each valve.

    I hope everyone has fun in Balty, I have to work.

  9. #9
    Join Date
    Sep 2004
    Location
    SoCal
    Posts
    446
    Mr. Freeze,
    Your right, I should RTFDS (Data Sheet). The Circon SCC300GPC has 4 control loop objects yet only 2 analog outputs.

    Ciao,
    lb

    Those who can - do, those who can't - teach, those who can't do either - manage.
    A hundred million nodes - it's a LON story.

  10. #10
    Join Date
    May 2002
    Posts
    9,564
    Maybe this one ....

    Add Me
    Then add one ilon100 and you are all set.

    Or a programmable Circon.........

    [Edited by sysint on 08-22-2005 at 07:11 AM]

  11. #11
    Join Date
    Mar 2005
    Location
    Pacific Time Zone
    Posts
    4,192
    Those other controllers mentioned are quite interesting. I'll have to look into them further for future jobs. I really just (kind of) know the TAC product.

    Freeze Stat - your right there is more engineering factors involved - wire length, topology, transformer sizing, etc. I was just using an example to show minimum hardware and if a controller dies vs. using all lon.

    LonBoy - Good point on free plug-ins, but don't forget the LM credits. ;o) I won't make the convention, but just for Scooter's it would be worth it if I wasn't so swamped with jobs. If anyone is going they'll have to hit you up for directions/meeting at Scooter's. Still is one of the best, if not the best meal I've ever had.
    "How it can be considered "Open" is beyond me. Calling it "voyeur-ed" would be more accurate." pka LeroyMac, SkyIsBlue, fka Freddy-B, Mongo, IndyBlue
    BIG Government = More Dependents
    "Any 'standard' would be great if it didn't get bastardised by corporate self interest." MatrixTransform
    http://threedevilskennel.com/ - not my website.
    Versatile Hunting Dog Federation - www.vhdf.org/


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