diff --git a/README.md b/README.md
index 9c9b212..38c98ac 100644
--- a/README.md
+++ b/README.md
@@ -77,4 +77,74 @@ Once that is done, restart domoticz:
 ``` shell
 sudo service domoticz.sh restart
 ```
+## ScreenShots
 
+TBD
+
+## Documentation about the registers used.
+
+This is a copy of : https://gist.github.com/alphp/95e1efe916c0dd6df7156f43dd521d53
+
+### Modbus holding registers:
+
+| Register(s) | Meaning         | Scale Unit | Data format    | R/W |
+|-------------|-----------------|------------|----------------|:---:|
+| 0000h-0001h | total energy    | 1/100 kWh  | unsigned dword |  Rą |
+| 0002h-0003h | reserved        |            | unsigned dword |     |
+| 0004h-0005h | reserved        |            | unsigned dword |     |
+| 0006h-0007h | reserved        |            | unsigned dword |     |
+| 0008h-0009h | export energy   | 1/100 kWh  | unsigned dword |  Rą |
+| 000Ah-000Bh | import energy   | 1/100 kWh  | unsigned dword |  Rą |
+| 000Ch       | voltage         | 1/10 V     | unsigned word  |  R  |
+| 000Dh       | current         | 1/100 A    | unsigned word  |  R  |
+| 000Eh       | active power    | 1 W        | signed   word  |  R  |
+| 000Fh       | reactive power  | 1 VAr      | unsigned word  |  R  |
+| 0010h       | power factor    | 1/1000     | unsigned word  |  R  |
+| 0011h       | frequency       | 1/100 Hz   | unsigned word  |  R  |
+| 0012h       | reserved        |            | unsigned word  |     |
+| 0013h       | reserved        |            | unsigned word  |     |
+| 0014h       | reserved        |            | unsigned word  |     |
+| 0015h:high  | station address | 1-247      | unsigned char  | R/W |
+| 0015h:low   | baud rate       | 1-4˛       | unsigned char  | R/W |
+| 001Ah       | relaył          |            | unsigned word  | R/W |
+
+#### Notes:
+
+##### Note 1:
+
+Total, export and import energy counters can erased writing 0 in total energy
+registers.
+
+##### Note 2:
+
+Value mapping, default 1.
+
+| Value | Baud rate |
+|:-----:|:---------:|
+| 1     | 9600 Bd   |
+| 2     | 4800 Bd   |
+| 3     | 2400 Bd   |
+| 4     | 1200 Bd   |
+
+##### Note 3:
+
+In DDS238-2 ZN/SR model the relay can be switched by 0x001A register.
+
+| Value | Relay |
+|:-----:|:-----:|
+|   0   |  Off  |
+|   1   |  On   |
+
+##### Data formats
+
+| Data format | Lenght  | Byte order |
+|-------------|--------:|------------|
+| char        |  8 bits |            |
+| word        | 16 bits | Big endian |
+| dword       | 32 bits | Big endian |
+
+
+### Writing registers
+
+The meter does not understand the 'write sigle register' function code (06h),
+only the 'write multiple registers' function code (10h).