(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 8 of 8

Thread: Reverse engineer Takagi tankless WH control protocol

Hybrid View

  1. #1
    "Retired" HVACR contractor - currently university professor KI7OM's Avatar
    Join Date
    Jul 2007
    Location
    Salt Lake City UT
    Posts
    5

    Default Reverse engineer Takagi tankless WH control protocol

    Iím wondering if anyone has reverse engineered Takagiís TK-x remote control protocol. Takagi uses a twisted pair for remote communication with any of the TK series tankless water heaters out to a TM-RE30 remote controller. The TM-RE30 is able to report inlet and outlet water temperature, flow rate, set point, time, and error codes. Up to this point I have only checked for the presence of DC (measured at about 15VCD) and the presence of an AC signal in the mV range. I have yet to put a oscilloscope on the line to determine the frequency of the AC or to capture any signaling. My interest is in integrating this information into a centralized residential energy management system.

  2. #2
    DIY Junior Member allan-sf's Avatar
    Join Date
    Apr 2012
    Location
    SF Bay Area, CA
    Posts
    1

    Default I would love to know too. Got the same setup.

    If you're in the Bay Area, my work has a lab of fairly expensive
    scopes and digital signal analyzers. Though it probably
    is some very simple rs-232 like protocol with that DC offset.

    I'm using mine for radiant hydronic, so getting data on usage
    and cycles would be nice, though it might be easier to
    use a fancier thermostat (thermostat turns on 2 pumps
    which triggers the Takagi)



    allan

  3. #3
    DIY Junior Member Jim Evans's Avatar
    Join Date
    Feb 2013
    Location
    Washington
    Posts
    3

    Default

    I have two Takagi JRs used for hydronic heat, and I just received a remote control unit for one of them. I'm thinking it's definitely worth my time to put a 'scope on it and check out the protocol and try to roll my own simple remote with an Arduino, rather than pay $80 for the second remote. I'll let you know if I have any success.

    -J

  4. #4
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,661

    Default

    If it is twisted pair it may be RS422.

    Are you wanting to build one ? Why reverse engineer it ?

    The protocol that it uses will depend on the type of CPU that it uses.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  5. #5
    Jack of all trades DonL's Avatar
    Join Date
    Mar 2011
    Location
    Houston, TX
    Posts
    3,661

    Default

    Quote Originally Posted by KI7OM View Post
    I’m wondering if anyone has reverse engineered Takagi’s TK-x remote control protocol. Takagi uses a twisted pair for remote communication with any of the TK series tankless water heaters out to a TM-RE30 remote controller. The TM-RE30 is able to report inlet and outlet water temperature, flow rate, set point, time, and error codes. Up to this point I have only checked for the presence of DC (measured at about 15VCD) and the presence of an AC signal in the mV range. I have yet to put a oscilloscope on the line to determine the frequency of the AC or to capture any signaling. My interest is in integrating this information into a centralized residential energy management system.

    You may find that Takagi uses a Honeywell protocol.

    This may be some nice reading for a energy management system integrator.

    http://www.prosoft-technology.com/co...M.OO.01.EN.pdf

    The Honeywell stuff is good.
    Last edited by DonL; 02-10-2013 at 09:27 AM.
    Theory only works perfect in a vacuum.

    Cyber Security Protection for Windows C:\ > WWW.WinForce.Net

  6. #6
    DIYer, not in the trades LLigetfa's Avatar
    Join Date
    Feb 2011
    Location
    NW Ontario, Canada
    Posts
    3,687

    Default

    Does the remote have a FCC ID? If so, you might be able to find some info on the FCC site. It's amazing how much one can glean from the FCC submissions. Barring that, if you (the OP) purchase and disassemble a unit, you might be able to identify the chipset used if they didn't sandblast or encase it in epoxy. There could be two-way communication so you may need to have one anyway if you want to eavesdrop on the conversation.

    One time I was emailing back and forth with an engineer at Carlon (Lamson & Sessions) trying to get some technical details for off-label use of one of their products. They were giving me the hard line of it being "proprietary" information to which I showed them a link to what was on the FCC site (99%) and I just wanted the last 1% of details. It didn't help.

    Sounds like an interesting project. The 15VDC is probably to power the remote and if it is a single twisted pair then that narrows down the list of communication protocols.

  7. #7
    DIY Junior Member Jim Evans's Avatar
    Join Date
    Feb 2013
    Location
    Washington
    Posts
    3

    Default

    The two wires have 22VDC on them. The heater unit blindly transmits a 20 bit packet 5 times a second at about 500bps burst. Just roughly looking at the bit patterns on the scope, I'm guessing it alternates between two types of packets. The remote, if connected, responds after every other packet with a 20 bit packet of its own. I'm not sure of the bit encoding, it does not have the distinctive look of I2C or the Honeywell protocol.

    I'm guessing it's just a simple proprietary frame, with the bit encoding being a .5ms pulldown for a 0 bit and a 1.5ms pulldown for a 1, repeated at 500bps. It could be some PSK encoding, but I don't think so.

    That's as much as I want to do with the 'scope. Next time I have time to sit down with it, I'll have an Arduino dump the frames and start looking at what the fields are in it and how it's encoded. I'm sure it's simple.

    Name:  takagi bits.jpg
Views: 102
Size:  44.4 KBName:  takagi packet.jpg
Views: 102
Size:  47.7 KB

  8. #8
    DIY Junior Member Jim Evans's Avatar
    Join Date
    Feb 2013
    Location
    Washington
    Posts
    3

    Default

    PS: in the second picture, the first, higher-amplitude packet is the transmission from the heater. The second, lower-amplitude packet is from the remote.

Similar Threads

  1. Replies: 1
    Last Post: 11-19-2011, 03:40 AM
  2. Takagi outdoor propane tankless tk3
    By HANKSTER in forum Tankless Water Heater Forum
    Replies: 1
    Last Post: 11-10-2011, 01:29 PM
  3. Delta Monitor Shower Valves and Takagi tankless heater problems
    By hptulsa in forum Shower & bathtub Forum & Blog
    Replies: 0
    Last Post: 10-27-2011, 11:56 AM
  4. Water Going Cold with Takagi Tankless
    By monty in forum Tankless Water Heater Forum
    Replies: 21
    Last Post: 05-28-2010, 11:09 AM
  5. Tankless H2O: Rheem vs. Takagi
    By teamviper in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 1
    Last Post: 02-15-2007, 04:35 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •