Before commissioning a PROFIBUS system, stations must be assigned unique addresses.
The PROFIBUS address of a DP slave can be adjusted in two ways:
1.Through settings on the device with the help of switches or another control interface.
2.By sending a special telegram via the PROFIBUS. Address 126 is reserved as the default address for a DP slave.
This second function is not necessarily supported by every DP slave. The entry
Set_Slave_Add_supp = 1
in the GSD file indicates whether this function is supported.
The address of a DP slave can only be changed in the state Wait Parameter (WPRM). Only when the DP slave is in this state can the master (typically a class 2 master) send a telegram to modify the DP slave's address. The master should first verify that the new address is actually free.
After the address has been changed, it is necessary to execute a cold-start (power supply off and on again) of the DP slave.
Address: telegram to change address with 4 bytes
New address |
Ident number High byte |
Ident number Low byte |
Extensions |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
Address byte 1: New address |
0–125 (0x00–0xFE) |
New address |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
Address byte 2 & 3: ident number |
0-255 (0x00-0xFF) |
Ident number high byte |
|||||||
0-255 (0x00-0xFF) |
Ident number low byte |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
Address byte 4: |
|
|
|
|
|
|
|
X |
Further changes of the address are not allowed |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Reserved |