RAMSES ESPProtocol
Technical background for those who want to use the gateway flow cards or the frame form.
A frame
Every packet on the bus is one line of text:
I --- 29:173894 29:233244 --:------ 22F1 003 000304| Part | Example | Meaning |
|---|---|---|
| Verb | I | I inform, RQ request, RP reply, W write |
| Sequence number | --- | Usually empty |
| Address 1 | 29:173894 | Sender |
| Address 2 | 29:233244 | Receiver (--:------ = nobody in particular) |
| Address 3 | --:------ | Sometimes the sender again (for broadcasts) |
| Code | 22F1 | Kind of message |
| Length | 003 | Number of bytes in the payload |
| Payload | 000304 | The content, in hex |
Over MQTT the ramses_esp wraps every frame as JSON: {"msg": " I --- 29:173894 ..."}. On rx the signal strength
(RSSI) comes along too.
Important codes
| Code | Name | Sent by | Content |
|---|---|---|---|
22F1 | Fan mode | Remote → unit | 00 RR SS: RR = mode, SS = brand-specific suffix (04, 06, 0A) |
22F3 | Boost / timer | Remote → unit | 00 UU DD: DD minutes (UU 00) or hours (UU 01). Orcon uses a long form. |
22F7 | Bypass | Homey → unit | 00 MM EF: auto, open or closed |
31D9 | Fan state | Unit | Mode or speed; see below |
31DA | Extended status | Unit | CO₂, humidity, temperatures, air flow, bypass, filter, faults |
10D0 | Filter | Unit / remote | Days until replacement; W 10D0 00FF resets the counter |
10E0 | Device info | All | Manufacturer and model, e.g. VMC-15RP01 |
1298 | CO₂ | Sensor | ppm |
12A0 | Humidity | Sensor / unit | % (sometimes with temperature) |
31E0 | Ventilation demand | CO₂ sensor | % |
2E10 | Presence | Sensor | |
1060 | Battery | Remote / sensor | Level and battery low |
2411 | Parameter | Unit ↔ Homey | Reading (RQ) and writing (W) heat recovery parameters |
1FC9 | Binding | All | Offer, accept, confirm |
Modes per brand
The same number in 22F1 means something different per brand:
| Byte | Orcon | Itho | Vasco / ClimaRad |
|---|---|---|---|
00 | away | off | off |
01 | low | away | away |
02 | medium | low | low |
03 | high | medium | medium |
04 | auto | high | high |
05 | auto | auto | |
07 | off |
That's why the unit has a Brand setting. The tables follow ramses_rf; the Orcon one is confirmed on a real unit.
31D9: mode or speed?
- With status byte
FFthe value is a speed in half percent. - With status byte
00(seen live as000000to000004) it's a step number. - Orcon reports its mode in byte 2 (00 away, 01 low, 02 medium, 03 high, 04 auto), not a speed.
Binding (1FC9)
Homey picks a free address that doesn't appear on the bus yet: 29: as a remote, 37: as a CO₂ sensor. When you
start binding from a unit, only the answer of that unit counts.
Echoes
The ramses_esp hears its own transmissions back. Homey recognises them as an echo: they don't count as a remote button press and they're marked in the bus view. A flow that controls the unit therefore never fires its own trigger.
Further reading
- ramses_rf: the Python library much of this knowledge comes from
- ramses_esp: the gateway firmware
- ramses_cc: the Home Assistant integration