http://www.ab-log.ru/smart-house/heating-automation/vaillant-rs232

5V TTL level serial but it also accepts 3.3V serial (tested with CP2102 which is 3.3V, but 5V tolerant)

1 Not used
2. +5 V (for the first version of the power adapter vrDIALOG, for the operation of the converter RS232-TTL)
3. RX (from the computer to the boiler)
4. TX (from the boiler to the computer)
5. Ground (earth)
6. +24 (Apparently new power adapter on bus eBUS)

Serial port is 9600 8N1

This is translated and extended version of protocol dump from link above to ease comparison with my boiler

The first line - that we send, the second - the answer of the boiler.
Third line (if exists is difference in my response)
In parentheses is the value that we get.

Something like initialize the connection.
# 07 02 00 00 00 04 C4
# 08 00 00 9E 0A 0C 6B FD
< 08 00 00 93 0B 09 FB 0B

Minimum design flow temperature
# 07 00 00 00 C2 01 7C
# 04 00 [# 23] 33
35 degrees

Start hysteresis
# 07 00 00 00 C3 01 7E
# 04 00 [# 02] 12
2 °

Hysteresis off
# 07 00 00 00 C4 01 70
# 04 00 [# 06] 16
6 °

Left before the service
# 07 00 00 00 AC 02 A3
# 05 00 [# 0B C2] #FC
3010 hours

Maximum temp filing for DHW
# 07 00 00 00 A6 01 B4
# 04 00 [# 55] 45
85 degrees

Maximum time the boiler heating
# 07 00 00 00 66 01 2D
# 04 00 [# 2D] 3D
45 degrees

Adjusting the outer t-pair (if connected to the boiler sensor outdoor t-ry)
# 07 00 00 00 65 01 2B
# 04 00 [# 00] 10
0 degrees

Maximum design temp boiler
# 07 00 00 00 E1 01 3A
# 04 00 [# 46] 56
70 degrees

Pump run after the end of heating (after turning off the burners)
# 07 00 00 00 64 01 29
# 04 00 [# 1E] 0E
30 minutes

Collector temperature (if also the boiler sensor is connected)
# 07 00 00 00 B8 02 8B
# 06 00 00 00 00 60
0 degrees

Maximum flow temperature heating (in my case only the range of 60 to 83 degrees)
# 07 00 00 00 A5 01 B2
# 04 00 [# 52] 42
82 degrees

Vrebya pump run after turning off the boiler
# 07 00 00 00 63 01 27
# 04 00 [# 12] 02
18 (180)

Shifting values ​​hotstart
# 07 00 00 00 9D 01 C2
# 04 00 07 17
7

Partial heat. Boiler
# 07 00 00 00 A9 01 AA
# 04 00 [# 01] 11
1 kW

Hours on GVS
# 07 00 00 00 22 02 A6
# 05 00 00 00 28
0

Cycles of heating
# 07 00 00 00 29 02 B0
# 05 00 00 [# 2B] 03
43

Cycles DHW
# 07 00 00 00 23 02 A4
# 05 00 00 00 28
0

There is a feedback controller
# 07 00 00 00 74 01 09
# 04 00 00 10
0 (OFF)

Status signal DCF
# 07 00 00 00 69 01 33
# 04 00 00 10
0 (no reception)

VUV Mittenstellung
# 07 00 00 00 45 01 6B
# 04 00 00 10
0 (OFF)

Counter 3 ignition attempts
# 07 00 00 00 6F 01 3F
# 04 00 0A 1A
10

Unsuccessful automatic ignition
# 07 00 00 00 1F 01 DF
# 04 00 0A 1A
10

Number of trips thermal protection
# 07 00 00 00 20 01 A1
# 04 00 00 10
0

Outdoor temperature
# 07 00 00 00 6A 03 37
# 06 00 FC 39 AA 63
-60.44

T-pa boiler SC down
# 07 00 00 00 B6 02 97
# 06 00 FF 21 AA 5F
-13.94

T ra feed
# 07 00 00 00 18 03 D3
# 06 00 01 76 00 88
23.38 / no errors

Start the timer by GVL
# 07 00 00 00 71 01 03
# 04 00 01 11
1 (ON)

Mode
# 07 00 00 00 08 01 F1
# 04 00 01 11
1 (winter)

Request to heat DHW C1 / C2
# 07 00 00 00 58 01 51
# 04 00 00 10
0 (OFF)

Ionisation current
# 07 00 00 00 73 02 04
# 05 00 FC EC 25
64748.00

Circulation pump for boiler layered
# 07 00 00 00 E0 01 38
# 04 00 00 10
0 (OFF)

Pumps UK
# 07 00 00 00 DF 01 46
# 04 00 00 10
0 (OFF)

The circulation pump
# 07 00 00 00 AF 01 A6
# 04 00 00 10
0 (OFF)

Pump heating boiler
# 07 00 00 00 01 9E C4
# 04 00 00 10
0 (OFF)

External heating pump
# 07 00 00 00 3F 01 9F
# 04 00 00 10
0 (OFF)

Built-in pump
# 07 00 00 00 44 01 69
0 (OFF)

Calc. temp an external regulator 7-8-9
# 07 00 00 00 25 02 A8
# 05 00 05 A0 82
90,00

Room thermostat
# 07 00 00 00 01 0E FD
# 04 00 00 10
0 (OFF)

The design temperature of the boiler
# 07 00 00 00 04 02 EA
# 05 00 00 F0 D8
15 degrees

The calculated flow temperature, the handle on the panel
# 07 00 00 00 19 02 D0
# 05 00 02 30 1C
35 degrees

The temperature of the boiler
# 07 00 00 00 17 03 CD
# 06 00 FF 21 AA 5F
-13.94 Degrees

The flow sensor HS
# 07 00 00 00 16 03 CF
# 06 00 FF 21 AA 5F
-13.94

Record the values ​​in the boiler:
The second byte is 0x80
The fifth byte - Register
Sixth byte - value
Seventh - CRC (checksum)

Example, set the value of the pump run - 31 minutes (value 0x1F)
Register 0x64
# 07 80 00 00 64 1F FF
If all goes well, the boiler will return the following sequence.
# 03 00 06