Siemens SIMATIC ET 200AL - Page 1277

Parameter assignment/addressing
3.6 Bus parameters
PROFIBUS with STEP 7 V13
54 Function Manual, 12/2014, A5E03775446-AC
Bus parameters for the bus profile of PROFIBUS subnets
Note
Display of offline values
The offline values of the bus parameters are always displayed even if they are connected
online with the target system.
Table 3- 2 Bus parameters - value ranges
Bus parameters
Adjustable
1
Limit values
Tslot_Init Yes Max. Tsdr + 15 <= Tslot_Init <= 16.383 t_Bit
Max. Tsdr Yes 35 + 2*Tset + Tqui <= Max. Tsdr <= 1,023 t_Bit
Min. Tsdr Yes 11 t_Bit <= Min. Tsdr <= MIN(255 t_Bit, ...
... Max. Tsdr - 1, 34 + 2*Tset + Tqui)
Tset Yes 1 t_bit <= Tset <= 494 t_bit
Tqui Yes 0 t_bit <= Tqui <= MIN(31 t_bit, Min. Tsdr - 1)
GAP factor Yes 1 <= GAP factor <= 100
Retry limit Yes 1 <= Retry limit <= 15
Tslot ( slot time) No -
Tid2 No Tid2 = Max. Tsdr
Trdy No Trdy = Min. Tsdr
Tid1 No Tid1 = 35 + 2*Tset + Tqui
Ttr (Target Rotation Time) Yes 256 t_Bit <= Ttr <= 16,777,960 t_bit
Ttr typical No This time is for information only and is not transmitted to
the devices.
Watchdog 10 ms <= Watchdog <= 650 s
1
depending on bus profile
User-defined bus profile
Use the following settings to create a user-defined bus profile:
● minimum Target Rotation Time (Ttr) = 5000x HSA (highest PROFIBUS address of an
active device)
● minimum watchdog (Watchdog) = 6250x HSA
Recalculate
Use the button "Recalculate" to recalculate the parameters.