NPM Motionnet G9001A, User Manual

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DA70131-1/3E
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6. How to calculate the communication cycle time
The calculations of the communication cycle time can be classified as follows:
K: Communication speed coefficient
Communication speed (Mbps) K
20 1
10 2
5 4
2.5 8
N: Number of local devices connected
B: Number of bytes of data to send (when sending 2 bytes of data: B = 2)
6-1. Time required for one cycle
Basic item Required time (
s )
Communication time required per local device (CT) 7.7 x K
Cycle time = (CT + 7.4) x N (
s )
Ex.: Calculating the cycle time with a communication speed of 20 Mbps and 30 local devices.
(7.7 x 1 + 7.4) x 30 = 453
 s
6-2. Time required for one complete data communication
There are two types of data communications as follows:
1) When there is data in the response from a local device (the data length is variable).
2) When there is no data in the response from a local device.
Basic item Required time (
s )
Data sending time (ST) (B x 0.6 + 3.25) x K
Response time with data (JT) (B x 0.6 + 5.65) x K
Response time without data (JT) 5.05 x K
One complete data communication cycle = ST + JT + 7.4 (
s )
6-3. Total time of cyclic communication (including data communication)
The total time can be obtained by adding the data communication times to the ordinary communication cycle
time.
Ex.1: Communication speed = 20 Mbps, 34 local devices are connected, and on 4 occasions the data
communication consisted of 2 bytes for sending and 6 bytes for receiving.
Cycle time = Cyclic time + (Data communication time) x Number of times of data communication
= (7.7 x 1 + 7.4) x 34 + {(2 x 0.6 + 3.25) x 1 + (6 x 0.6 + 5.65) x 1 + 7.4} x 4
= 513.4 + 21.1 x 4
= 597.8
 s
Note: The formula above contains some margin for error. In actual operation, a shorter total time can be
obtained.
However, if a communication error occurs, the total time will be longer than the calculated time.