Example 2: Writing to an user register
 | Code word In normal mode all user registers are read-only with the exception of Register 31. In order to deactivate this write protection you must write the code word (0x1235) into Register 31. If a value other than 0x1235 is written into Register 31, write protection is reactivated. Please note that changes to a register only become effective after restarting the terminal (power-off/power-on). |
I. Write the code word (0x1235) into Register 31.
Output Data
Byte 0: Control byte | Byte 1: DataOUT1, high byte | Byte 2: DataOUT1, low byte |
|---|---|---|
0xDF (1101 1111bin) | 0x12 | 0x35 |
Explanation:
- Bit 0.7 set means: Register communication switched on.
- Bit 0.6 set means: writing to the register.
- Bits 0.5 to 0.0 specify the register number 31 with 01 1111bin.
- The output data word (byte 1 and byte 2) contains the code word (0x1235) for deactivating write protection.
Input Data (answer of the Bus Terminal)
Byte 0: Status byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0x9F (1001 1111bin) | 0xXX | 0xXX |
Explanation:
- The terminal returns a value as a receipt in the status byte that differs only in bit 0.6 from the value of the control byte.
- The input data word (byte 1 and byte 2) is of no importance after the write access. Any values still displayed are invalid!
II. Read Register 31 (check the set code word)
Output Data
Byte 0: Control byte | Byte 1: DataOUT1, high byte | Byte 2: DataOUT1, low byte |
|---|---|---|
0x9F (1001 1111bin) | 0xXX | 0xXX |
Explanation:
- Bit 0.7 set means: Register communication switched on.
- Bit 0.6 not set means: reading the register.
- Bits 0.5 to 0.0 specify the register number 31 with 01 1111bin.
- The output data word (byte 1 and byte 2) has no meaning during read access.
Input Data (answer of the Bus Terminal)
Byte 0: Status byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0x9F (1001 1111bin) | 0x12 | 0x35 |
Explanation:
- The terminal returns the value of the control byte as a receipt in the status byte.
- The terminal returns the current value of the code word register in the input data word (byte 1 and byte 2).
III. Write to Register 32 (change contents of the feature register)
Output data
Byte 0: Control byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0xE0 (1110 0000bin) | 0x00 | 0x02 |
Explanation:
- Bit 0.7 set means: Register communication switched on.
- Bit 0.6 set means: writing to the register.
- Bits 0.5 to 0.0 indicate register number 32 with 10 0000bin.
- The output data word (byte 1 and byte 2) contains the new value for the feature register.
CAUTIONThe value of 0x0002 given here is just an example!
The bits of the feature register change the properties of the terminal and have a different meaning, depending on the type of terminal. Refer to the description of the feature register of your terminal (chapter Register description) regarding the meaning of the individual bits before changing the values.
Input data (response from the Bus Terminal)
Byte 0: Status byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0xA0 (1010 0000bin) | 0xXX | 0xXX |
Explanation:
- The terminal returns a value as a receipt in the status byte that differs only in bit 0.6 from the value of the control byte.
- The input data word (byte 1 and byte 2) is of no importance after the write access. Any values still displayed are invalid!
IV. Read Register 32 (check changed feature register)
Output Data
Byte 0: Control byte | Byte 1: DataOUT1, high byte | Byte 2: DataOUT1, low byte |
|---|---|---|
0xA0 (1010 0000bin) | 0xXX | 0xXX |
Explanation:
- Bit 0.7 set means: Register communication switched on.
- Bit 0.6 not set means: reading the register.
- Bits 0.5 to 0.0 indicate register number 32 with 10 0000bin.
- The output data word (byte 1 and byte 2) has no meaning during read access.
Input Data (answer of the Bus Terminal)
Byte 0: Status byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0xA0 (1010 0000bin) | 0x00 | 0x02 |
Explanation:
- The terminal returns the value of the control byte as a receipt in the status byte.
- The terminal returns the current value of the feature register in the input data word (byte 1 and byte 2).
V. Write Register 31 (reset code word)
Output Data
Byte 0: Control byte | Byte 1: DataOUT1, high byte | Byte 2: DataOUT1, low byte |
|---|---|---|
0xDF (1101 1111bin) | 0x00 | 0x00 |
Explanation:
- Bit 0.7 set means: Register communication switched on.
- Bit 0.6 set means: writing to the register.
- Bits 0.5 to 0.0 specify the register number 31 with 01 1111bin.
- The output data word (byte 1 and byte 2) contains 0x0000 for reactivating write protection.
Input Data (answer of the Bus Terminal)
Byte 0: Status byte | Byte 1: DataIN1, high byte | Byte 2: DataIN1, low byte |
|---|---|---|
0x9F (1001 1111bin) | 0xXX | 0xXX |
Explanation:
- The terminal returns a value as a receipt in the status byte that differs only in bit 0.6 from the value of the control byte.
- The input data word (byte 1 and byte 2) is of no importance after the write access. Any values still displayed are invalid!