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Bus parameter
Range of values *
(default setting) **
Tset
1...255 *
(1...240)
Tqui
0...10 *
(0...9)
GAP Factor
1...100 *
(10...1000)
Retry limit
1...15 *
(1...10)
Tid2
55...980
Calculated value
Trdy
11...150
Calculated value
Tid1
37...515
Calculated value
Ttr
256...16777960 *
(0...49888)
Ttr (ms)
Calculated value
* value can only be defined under "User-defined" profile; value range depending on transmission speed.
** Default: Values depending on the profile and transmission speed.
*** The parameter values are specified in t_Bit. Exception: Ttr (ms)
Bit time (t_Bit)
The bit time is the time that elapses when sending a bit. It is calculated from the reciprocal
value of the transmission speed.
Using the "Bit time" unit has the advantage that the bus parameters can be specified
independently of the transmission speed used.
To calculate the time in milliseconds from the number of bit time units, use the following
formula:
SIMATIC CC7
Operating Instructions, 10/2019, C79000-G8976-C503-02
Meaning ***
Trigger time [t_Bit]
The trigger time is the time that can elapse in the station between receiving
a data frame and reacting to it.
Modulator quiet time [t_Bit]
The modulator quiet time is the time that a sending station needs to switch
from send to receive after frame end.
The gap update factor specifies how many token round trips occur before a
new active station can be included in the logical token ring.
This parameter specifies the maximum number of attempts (frame repeti-
tions) allowed to access a station.
Idle time 2 [t_Bit]
Idle time 2 defines the minimum amount of time after sending an
unacknowledged frame after which a sending station can send the next
frame.
Ready time [t_Bit]
The ready time specifies the minimum amount of time after which a sending
station can receive a response frame.
Idle time 1 [t_Bit]
Idle time 1 defines the minimum amount of time after receiving an answer
after which a sending station can send the next frame.
Target Rotation Time [t_Bit]
The target rotation time is the maximum length of time available for a token
round trip. During this time, all active stations (DP master etc.) are in pos-
session of the token once. The difference between the target rotation time
and the actual token holding time of a station determines the length of time
remaining for the other active stations (PG, additional DP masters etc.) to
send frames.
Recommendation for the value: 5000 * "Highest PROFIBUS address"
Target Rotation Time [milliseconds], calculated from "Ttr".
Configuration
4.6 Interface configuration
61
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