YASKAWA MP920 User Manual page 77

5 215IF Module
5.4.4 Tokens
• Transmission speed: 1 Mbps
Transmission cycle (ms)
= 0.31 × station No. + 0.016 × total number of link transmission words
+ message transmission margin (≥ 4.8 ms)
Note: 1. The token cycle time does not guarantee data transmission in any
specific cycle or a fixed cycle.
2. Do not set the token cycle time to a value less than the value calcu-
lated using the above equations. Engineering from the MPE720
may no longer be possible.
3. Each parameter in the above equations depends on the hardware
and software version number of the transmission interface board,
the system configuration, and other factors in the system. The val-
ues should be used only as a guide for system design.
Estimation of the Maximum Number of CP-215 Stations Connected
By modifying the above equations, the maximum number of stations that can be connected
can be estimated for the token cycle time. The results are shown in the following table.
Table 5.2 Estimation of the Maximum Number of Stations Connected
Number of Link Transmission
Transmission Cycle (ms)
Words
1,024 Words
2,048 Words
Note: The number of stations connected is restricted not only by the trans-
mission performance, but also by electrical conditions, such as the
number of stations connected and the transmission distance.
4 Mbps
10
30 stations
20
64 stations
30
64 stations
50
64 stations
100
64 stations
−
10
20
64 stations
30
64 stations
50
64 stations
100
64 stations
5-16
Transmission Speed
2 Mbps 1 Mbps
− −
−
40 stations
64 stations 28 stations
64 stations 64 stations
64 stations 64 stations
− −
−
5 stations
−
48 stations
64 stations 40 stations
64 stations 64 stations