Communication Time - Mitsubishi Electric MELSEC FX Series User Manual

FX communication
7.5.3

Communication Time

This is to explain the method of calculating the approximate time until all communication is over.
For the locations of T0 to T4, see the previous page.
1 ) When reading data from the programmable controller to the computer
Communication time = T0 + (T1 + T2 or TW, whichever is longer) + T3 + T4 + T5
T0, T3, T5 =1/baud rate × number of bits in 1 character (1 + 7(8) + 0(1) + 1(2))
T1 =max. 1 scan time (during RUN, message processing is done at END processing, a
maximum delay of 1 scan could occur depending on message timing; during STOP ,
T1 is 1 ms)
T2 =END process time of programmable controller during data communication
T4 =A delay of at least 2 scans is required. However, using one-pair wiring on the 1:N
system configuration, this time need to set "Time-out timer value (D8129) + 1 scan
time" or more.
TW = set time when message wait is set.
2 ) When writing data from the computer to the programmable controller
Communication time = T0 + (T1 + T2 or TW, whichever is longer) + T3
T0, T3 =1/baud rate × number of bits in 1 character (1 + 7(8) + 0(1) + 1(2))
× number of characters
T1 =max. 1 scan time (during RUN, message processing is done at END processing, a
maximum delay of 1 scan could occur depending on message timing; during STOP ,
T1 is 1 ms)
T2 =END process time of programmable controller during data communication
TW = set time when message wait is set.
× number of characters
Start bit
Data length (7 or 8)
Start bit
Data length (7 or 8)
Computer link 7
Stop bit (1 or 2)
Parity bit (0 or 1)
Stop bit (1 or 2)
Parity bit (0 or 1)
7-13
7