Omron CJ1W-DRM21 Operation Manual page 221

Communications Cycle Time Calculation
Use the equations shown below to calculate the communications cycle time (T
one Master. Note that if the result of this calculation is less than 2 ms, the actual communications
cycle time will be 2 ms.
= Σ (Communications time per Slave)
T
RM
+ High-density Unit processing time
+ Explicit message communications time
+ COS/Cyclic connection time (ms)
+ 0.01 × N + 1.0 [ms]
Communications Time per Slave:
This is the communications time required for a single Slave.
"Σ (Communications time per Slave)" represents the total of the "Communications time per Slave"
for all the Slaves in the network.
High-density Unit Processing Time:
3.5 ms
This is added if there are any Slaves in the network that use at least 8 bytes for input, output, or
both.
Explicit Message Communications Time:
(0.11 × T ) × n [ms]
B
The explicit message communications time is added as a delay time when explicit communications
(sending or receiving) are performed.
n= Number of explicit messages (both sending and receiving) that occur simultaneously within one
CPU Unit task period of CPU Unit
T = The baud rate factor
B
(500 kbit/s: T
COS/Cyclic Connection Time:
{(0.05+0.008 × S) × T
The COS/cyclic connection time is added as a delay time when COS/cyclic communications are per-
formed.
S: Total number of inputs and outputs in the COS/cyclic connection (bytes)
T : The baud rate factor
B
(500 kbit/s: T
n: Number of nodes occurring simultaneously within 1 communications cycle time in the COS/Cyclic
connection
N: Number of Slaves
Communications Time/Slave
The communications time per Slave is the communications time required for a single Slave.
The following equations show the communications time/Slave (T
The communications time for each slave is not related to the type of connection (protocol) used by the
slave.
Output Slaves with Less Than 8 Bytes of Output
= 0.016 ×T
T
RT
S
OUT1
T :
B
(500 kbit/s: T
CJ-series DeviceNet Units Operation Manual for NJ-series CPU Unit(W497)
= 2; 250 kbit/s: T = 4; 125 kbit/s: T
B B
} × n (ms)
B
= 2; 250 kbit/s: T = 4; 125 kbit/s: T
B B
× S + 0.11 × T
+ 0.07 [ms]
B OUT1 B
: The number of Output Slave output words
The baud rate factor
= 2; 250 kbit/s: T
B B
8 Communications Timing
= 8)
B
= 8)
B
) for each kind of Slave Unit.
RT
= 4; 125 kbit/s: T = 8)
B
) for a network with
RM
8-3
8