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Remote I/O Communications Characteristics
Refresh Time (T
)
RF
Note
Master Units for CS, CJ,
C200HX/HG/HE (-Z), and
C200HS PLCs
Note
Slice Bus
Communications
Cycle Time (T
)
SL
Communications Unit
Processing Time
(T
and T
)
SL-CI
SL-CO
T
: The output byte transmission time
BYTE-OUT
B
: The number of output bytes
OUT
Baud rate
500 kbps
0.306 ms
250 kbps
0.542 ms
125 kbps
1.014 ms
The number of output bytes (B
input bytes (B
) is 0 for Output Slaves.
IN
The refresh time is the time required to exchange I/O data between the PLC's
CPU Unit and the DeviceNet Master Unit. The PLC's cycle time is increased
when a Master Unit is mounted, as shown below.
Refer to the PLC's operation manual for more details on the refresh time and
the PLC's cycle time.
When a Master Unit is mounted to the PLC, the PLC's cycle time (I/O refresh-
ing) is increased by the amount shown in the following table.
Process
I/O refreshing
DeviceNet Unit I/O refreshing:
• For CS/CJ-series Master Unit:
0.7 + 0.001 × number of words (ms) (See note.)
• For C200HX/HG/HE (-Z) PLCs:
1.72 + 0.022 × number of words (ms) (See note.)
• For C200HS PLCs:
2.27 + 0.077 × number of words (ms) (See note.)
The number of words refreshed is the total number of words in the I/O Area
that are allocated to the Slaves, including any unused words between those
words actually used by the Slaves. For example, if there are only two Input
Slaves with node addresses 1 and 5, the 5 input words for nodes 1 through 5
would be refreshed even though the input words for nodes 2, 3, and 4 are
unused.
If message communications are being performed, just add the number of
words used in message communications to the above number of words for
whenever messages are being processed.
The Slice bus communications cycle time is the delay in the Slice I/O Terminal
from the end of communications with one I/O Unit until the start of communi-
cations with the next Unit.
T
=
0.66
SL
+ (total number of input bytes of word Input Units) × 0.011
+ (total number of input bits of bit Input Units) × 0.009
+ (total number of output bytes of word Output Units) × 0.004
+ (total number of output bits of bit Output Units) × 0.001 [ms]
The DeviceNet Communications Unit processing time is the time required for
software processing in the Communications Unit. The processing time is dif-
ferent for input data and output data, as shown below.
T
= 0.71 + total number of input data bytes × 0.003 [ms]
SL-CI
T
= 0.2 + total number of output data bytes × 0.001 [ms]
SL-CO
T
T
OH
BYTE-IN
0.040 ms
0.073 ms
0.139 ms
) is 0 for Input Slaves, and the number of
OUT
Processing time
Section 5-1
T
BYTE-OUT
0.036 ms
0.069 ms
0.135 ms
65
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