Token Rotation Comparison; Token Rotation Time Versus Number Of Stations And Amount Of Data At 9.6 Kbaud - Siemens SIMATIC S7-200 System Manual

Token hold time (T
Token rotation time (T
where n is the number of data characters (bytes)
and m is the number of masters
Solving for the token rotation time using the example shown above, where each of the six
masters has the same token hold time, yields:
T (token hold time)
T (token rotation time) = 151.25 ms/master
(One "bit time" equals the duration of one signaling period.)
Figure 7-30

Token Rotation Comparison

Table 7-12, Table 7-13, and Table 7-14 show comparisons of the token rotation
time versus the number of stations and amount of data at 9.6 kbaud, 19.2 kbaud,
and 187.5 kbaud, respectively. The times are figured for a case where you use the
Network Read (NETR) and Network Write (NETW) instructions with the CPU or
other master devices.
Table 7-12 Token Rotation Time versus Number of Stations and Amount of Data at 9.6 kbaud
Bytes Transferred Bytes Transferred
per Station at
2
9.6 kbaud
stations
1 0.30
2 0.30
3 0.30
4 0.30
5 0.30
6 0.31
7 0.31
8 0.31
9 0.31
10 0.32
11 0.32
12 0.32
13 0.32
14 0.33
15 0.33
16 0.33
S7-200 Programmable Controller System Manual
A5E00066097-02
Setting Up Communications Hardware and Network Communications
) = (128 overhead + n data char)
hold
) = T of master 1 + T
rot hold
= (128 + 4 char)
= 151.25 ms/master
= 907.5 ms
Formulas for Token Hold Time, Token Rotation Time, Using NETR and NETW
Number of Stations, with Time in Seconds
3 4 5
stations stations stations
0.44 0.59 0.74
0.45 0.60 0.74
0.45 0.60 0.75
0.45 0.61 0.76
0.46 0.61 0.76
0.46 0.61 0.77
0.46 0.62 0.77
0.47 0.62 0.78
0.47 0.63 0.78
0.47 0.63 0.79
0.48 0.64 0.80
0.48 0.64 0.80
0.48 0.65 0.81
0.49 0.65 0.81
0.49 0.66 0.82
0.50 0.66 0.83
11 bits/char 1/baud rate
of master 2 + . . . + T
hold hold
11 bits/char 1/9600 bit times/s
6 masters
6 7
stations stations stations
0.89 1.03 1.18
0.89 1.04 1.19
0.90 1.05 1.20
0.91 1.06 1.21
0.91 1.07 1.22
0.92 1.07 1.23
0.93 1.08 1.24
0.94 1.09 1.25
0.94 1.10 1.26
0.95 1.11 1.27
0.96 1.11 1.27
0.96 1.12 1.28
0.97 1.13 1.29
0.98 1.14 1.30
0.98 1.15 1.31
0.99 1.16 1.32
of master m
8 9 10
stations stations
1.33 1.48
1.34 1.49
1.35 1.50
1.36 1.51
1.37 1.52
1.38 1.54
1.39 1.55
1.40 1.56
1.41 1.57
1.42 1.58
1.43 1.59
1.44 1.60
1.45 1.62
1.46 1.63
1.47 1.64
1.49 1.65
7-45