Siemens SIMATIC S5 Manual page 193

DB1 Parameters, DB1 PAFE, TRT
Example of Calculating the Target Rotation Time
Four active and two passive stations are connected to the SINEC L2 network.
TLN of the active stations:
TLN of the passive stations:
HSA:
BDR:
SET:
ST:
SDT1:
SDT2:
Data traffic for
• Station 1: ZP master
PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 2:
PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 3;
PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 4
• Station 2: PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 1
• Station 3: PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 1
• Station 4: PLC to PLC conn. SDA frame with 30 bytes of transmit data to station 1
Calculation of the basic frame load and the required time:
Token frames:
Station 1: 1·SRD with 6
1·SRD with 20 bytes of net data
3·SDA with 30 bytes of net data
Station 2: 1·SDA with 30 bytes of net data
Station 3: 1·SDA with 30 bytes of net data
Station 4: 1·SDA with 30 bytes of net data
Target rotation time to set:
Tip to optimize the target rotation time:
• Assign the station addresses in ascending order (1, 2, ...).
A-6
1, 2, 3, and 4
40, 41
4
500 kBaud
0
400 bit time units
12 bit time units
360 bit time units
SRD frame with 4 bytes of transmit data to station 40:
2 bytes of received data from station 40;
SRD frame with 10 bytes of transmit data to station 41;
10 bytes of received data from station 41
4·145
bytes of net data 500+6·11
500+20·11
3·(425+30·11)
425+30·11
425+30·11
425+30·11
Sum (rounded up):
6400 bit time units ·
= 580 bit times units
= 566 bit times units
= 720 bit times units
= 2265 bit times units
= 755 bit times units
= 755 bit times units
= 755 bit times units
= 6400 bit times units
1
= 12800 µs
500 kBaud
EWA 4NEB 812 6112-02
S5-95U, SINEC L2