Mitsubishi MELSEC LJ71C24, Руководство пользователя

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App. - 76 App. - 76
APPENDIXES
Appendix 7 Processing Time
(1) Time required to process communication using the nonprocedural
protocol (guideline)
The processing time for the Output and Input instructions can be estimated by
the following formula. Note, however, that the processing time may become
longer depending on other communication functions (e.g., communication using
the MC protocol) and special functions (e.g., ASCII-binary conversion,
transmission control) that are used at the same time.
The value obtained from the following formula is considered to be the processing
time taken for reception or transmission only when CH1 only is used (RS-232
connection).
(a) Output instruction
Tp = St + (D
le
/Cr 1000 + 0.07) Ds + T1
Tp ( 1) : The time from the start of execution of the Output instruction
to the End processing of the sequence scan at the
completion of the Output instruction execution (ms)
St : Scan time
D
le
: Data length of 1 byte at data transmission (number of bits)
Cr : Communication rate (bps)
Ds : Number of bytes of transmission data
T1 : C24 T1 = 3.0
1 This stands for the time range of processing (Tp).
Sequence program
Transmission command
Output instruction
Output instruction
complete device
OUTPUT
Step 0 END
Tp
One scan
C24 side
External device side
Transmission data
Start of the Output
instruction execution Start of the End processing of
the scan at the completion of
the Output instruction execution
[Calculation example]
Estimate the time required to process the Output instruction when
transmitting 100 bytes of data using the nonprocedural protocol with C24.
(Unit: ms)
• Scan time : 10 ms
• Data length : 10 bits (1 start bit, 8 data bits, 1 stop bit, no parity
bit)
• Communication rate : 19200 bps
10 + (10/19200 1000 + 0.07) 100 + 3.0 72.08 (ms)