Table of Contents
Advertisement
3 SPECIFICATIONS
3.5 Communication Performance
3.5.1 Link scan time
3 - 48
The link scan time represents a time during which the QJ71DN91 waits for responses
from all nodes after sending a polling request or bit-strobe requests.
The following shows the link scan time calculation formulas.
LS = (TIn + TOn + 0.097) + 0.222
LS:
Link scan time [ms]
TIn:
Transmission time for data received from the n-th slave. [ms] (Refer
to (1) below.)
TOn:
Transmission time for data sent to the n-th slave. [ms] (Refer to (2)
below.)
:
Indicates that the values in the parentheses "( )" must be added up
for all of the slave nodes. (Except for reserved nodes)
BR:
Coefficient corresponding to the baud rate
500kbaud = 1, 250kbaud = 2, 125kbaud = 4
(1) How to calculate TIn
(a)
When the length of the data received from the n-th slave is 8 bytes or less
TIn = BT + BTa
BT, BTa: Coefficient corresponding to the baud rate (See *1.)
(b)
When the length of the data received from the n-th slave is 9 bytes or more
TIn = (BT + BTa
BT, BTa: Coefficient corresponding to the baud rate (See *1.)
a:
b:
(2) How to calculate TOn
(a)
When the length of the data sent to the n-th slave is 8 bytes or less
TOn = BT + BTa
BT, BTa: Coefficient corresponding to the baud rate (See *1.)
(b)
When the length of the data sent to the n-th slave is 9 bytes or more
TOn = (BT + BTa
BT, BTa: Coefficient corresponding to the baud rate (See *1.)
c:
d:
*1 The following shows the coefficients corresponding to the baud rates.
BT
BTa
BR + 1.0 [ms]
Receive data length (bytes) [ms]
8 + 0.190)
a + {BT + BTa
Result obtained by dividing the receive data length by 7
(Truncate the fractional part.)
Remainder obtained by dividing the receive data length by
7
Transmit data length (bytes) [ms]
8 + 0.130)
c + {BT + BTa
Result obtained by dividing the transmit data length by 7
(Truncate the fractional part.)
Remainder obtained by dividing the transmit data length by 7
125kbaud
0.376
0.064
MELSEC-Q
(b + 1) + 0.450} [ms]
(d + 1) + 1.2} [ms]
250kbaud
0.188
0.032
500kbaud
0.094
0.016
3 - 48
Advertisement
Table of Contents
Troubleshooting
