Example 2: Writing To An User Register - Beckhoff KL400 Series Documentation

Access from the user program
• The terminal returns the firmware version 0x3341 in the input data word (byte 1 and byte 2). This is to
be interpreted as an ASCII code:
◦ ASCII code 0x33 represents the digit 3
◦ ASCII code 0x41 represents the letter A
The firmware version is thus 3A.
5.6.2

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
Note
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
0xDF (1101 1111 )
bin
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 1111
• 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
0x9F (1001 1111 )
bin
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
0x9F (1001 1111 )
bin
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 1111
• The output data word (byte 1 and byte 2) has no meaning during read access.
38
Byte 1: DataOUT1, high byte
0x12
Byte 1: DataIN1, high byte
0xXX
Byte 1: DataOUT1, high byte
0xXX
Version: 4.0
Byte 2: DataOUT1, low byte
0x35
.
bin
Byte 2: DataIN1, low byte
0xXX
Byte 2: DataOUT1, low byte
0xXX
.
bin
KL400x