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Chapter 2 Specification of Communication port for CPU module

2 – 28

[About Transmission interval design of ASR communication]

ASR communication is set to the lower priority than Task code communication in communication processing.

Therefore, the time which subtracts the task code processing time from the communication processing time is a time

given to ASR communication. And if the processing of whole ASR communication is completed within this time, the

set transmission interval is not kept and transmission delay will occur. Refer to the following examples in designing

the transmission interval of ASR communication.

Example 1) ASR communication: Using 4 ports (each 32 words)

Task code port: using 1 port (each 32-word monitor)

[ASR transmission processing time] = (0.0066 × 32 [word] + 3.7) × 4 [port] = 15.6 [ms]

[Task code processing time] = (0.1 × 32 [word + 5.0) ×1 [port] = 8.2 [ms]

[Communication processing time] = [ASR transmission processing time] + [Task code processing

time]= 15.6 + 8.2 = 23.8 [ms]

In the above case, the delay does not occur on transmission cycle in this condition because the time the

main processor can be operated in the communication processing is 32.1ms.

Example 2) ASR communication: Using 1 port (256 words)

Task code port: Using 3 ports (each 32-word monitor)

[ASR transmission processing time] = (0.0066 × 256 [word] + 3.7) × 1[port] = 5.4[ms]

[Task code processing time] = (0.1 × 38[word] + 5.0) ×3[port] = 26.4[ms]

[Communication processing time] = [ASR transmission processing time] + [Task code processing

time]= 5.4 + 26.4 = 31.8[ms]

In the above case, the delay may occur on transmission cycle occasionally because the time the main

processor can be operated in the communication processing is 32.1ms.

Example 3) ASR communication: Using 4 ports (256 words)

Task code port: Using 2 ports (each 64-word monitor)

[ASR transmission processing time] = (0.0066 × 256[word] + 3.7) ×4[port] = 21.6[ms]

[Task code processing time] = (0.1 × 64[word] + 5.0) × 2[port] = 22.8[ms]

[Communication processing time] = [ASR transmission processing time] + [Task code processing

time] = 21.6 + 22.8 = 44.4[ms]

In the above case, the delay occur on transmission cyclic in this condition because the time the main

processor can be operated in the communication processing is 32.1ms.

[In order that the delay does not occur on communication processing]

According to the calculation methods in the preceding paragraph, when enough communication processing time

cannot be obtained within 40ms cycle or when the expected communication response cannot be got, obtain the

communication processing time by adjusting the following three items.

- The number of communication port to be used (ASR communication and Task code communication)

- The number of communication words

- System processing time

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RTS WM300 Especificaciones Pagina 42