Page 1 of 1

iSense Thermostat power low?

PostPosted: Sat Jan 12, 2019 4:18 pm
by caddyblack

I have assambled the Nodo shop OTBW board in combination with the NodeMCU wifi module.
After connecting the board my Remeha iSense thermostat (V19) has dimmed/blinking light.
Looks like there is not enough current coming from the OTGW to feed the iSense. :(
Is this a known problem? Power supply connected to the OTGW board is at 24V and can deliver 2.3 Amps.

Additional info: My iSense does not have batteries installed. The opentherm 2 wires are the only power source. Do other people have to install batteries in the iSense to get itworking..

Re: iSense Thermostat power low?

PostPosted: Tue Jan 15, 2019 9:39 pm
by caddyblack
Update: Inserted batteries in the iSense.
All working well now (OTGW and iSense). :)

Re: iSense Thermostat power low?

PostPosted: Tue Jan 15, 2019 9:51 pm
by hvxl
The iSense (V19) should be able to work fine without batteries. For this to be initialized properly, the iSense has to be connected to the gateway while it already has the correct firmware and is operating in gateway mode. It is also helpful if the gateway has the current date and time.

So, this procedure should work:
  1. Rip the iSense off the wall.
  2. Make sure the OTGW has the correct FW and is operating in GW mode: PR=A (should return "PR: A=OpenTherm Gateway"), GW=1
  3. On the Thermostat Configuration screen of OTmonitor, select "Send the current date to the gateway" and "Send the current year to the gateway", then click "Set Clock"
  4. Within one minute, reconnect the iSense
In the OTmonitor log tab you may then expect to see the following sequence of events:
  • Thermostat connected
  • iSense setting the Max Rel Modulation level to 100% (twice)
  • iSense requesting the Day of week and time of day, which is provided by the OTGW
  • iSense requesting the Year, which is provided by the OTGW
  • iSense requesting the Date, which is provided by the OTGW
  • iSense reporting the Master configuration, which should have HB:0 (Smart Power) set.
  • OTGW acknowledges the Master configuration with HB:0 (Smart Power) set.
  • iSense switches to high power, reported by the OTGW to the log: High power
  • iSense reading the status in high power mode (to confirm it works)
  • iSense switching to low power, then to medium power.
  • Messages being exchanged in medium power mode.
  • After some time the backlight of the iSense turns off and the iSense switches back to low power mode.
  • When you press a button on the iSense, the backlight comes on and in the OTmonitor log you see: Medium power
As an example, here's an log I made long ago of such an event:

Code: Select all
18:27:55.016634 Thermostat connected
18:27:57.137923 T900E6400 Write-Data Maximum relative modulation level: 100.00
18:27:57.228014 B500E6400 Write-Ack  Maximum relative modulation level: 100.00
18:27:58.148532 T900E6400 Write-Data Maximum relative modulation level: 100.00
18:27:58.318613 B500E6400 Write-Ack  Maximum relative modulation level: 100.00
18:27:59.159259 T00140000 Read-Data  Day of week and time of day: Unk 00:00
18:27:59.329411 BF0140000 Unk-DataId Day of week and time of day: Unk 00:00
18:27:59.330854 A4014321B Read-Ack   Day of week and time of day: Mon 18:27
18:28:00.181425 T80160000 Read-Data  Year: 0
18:28:00.366979 B70160000 Unk-DataId Year: 0
18:28:00.367991 AC01607DE Read-Ack   Year: 2014
18:28:01.201373 T80150000 Read-Data  Date: Unk 0
18:28:01.332044 B70150000 Unk-DataId Date: Unk 0
18:28:01.333514 A40150609 Read-Ack   Date: Jun 9
18:28:02.211617 T1002010B Write-Data Master configuration: 00000001 11
18:28:02.322846 B7002010B Unk-DataId Master configuration: 00000001 11
18:28:02.324172 AD002010B Write-Ack  Master configuration: 00000001 11
18:28:02.411245 High power
18:28:03.231542 T00000000 Read-Data  Status: 00000000 00000000
18:28:03.321620 BC0000000 Read-Ack   Status: 00000000 00000000
18:28:03.381455 Low power
18:28:03.451745 Medium power
18:28:04.242086 T00030000 Read-Data  Slave configuration: 00000000 0
18:28:04.342139 B4003410B Read-Ack   Slave configuration: 01000001 11
18:28:05.297638 T00050000 Read-Data  Application-specific flags: 00000000 0
18:28:05.442711 BC00500FF Read-Ack   Application-specific flags: 00000000 255
18:28:06.273285 T00060000 Read-Data  Remote parameter flags: 00000000 00000000
18:28:06.413356 BC0060303 Read-Ack   Remote parameter flags: 00000011 00000011
18:28:07.293884 T80640000 Read-Data  Remote override function: 00000000
18:28:07.404706 B70640000 Unk-DataId Remote override function: 00000000
18:28:07.406333 A40640000 Read-Ack   Remote override function: 00000000
18:28:08.305741 T001D0000 Read-Data  Solar storage temperature: 0.00
18:28:08.405148 BF01D0000 Unk-DataId Solar storage temperature: 0.00

If that is not what you see, please provide a log of what happens when you connect your iSense.