Omron CS1W-ETN01 Operation Manuals page 88

Sending Commands From a PC
SEND(090)
CPU Bus Unit Service
Cycle
CPU Bus Unit Service
Processing Time
Transmission Processing
Time
Reception Processing
Time
CPU Data Set Processing
Time
Example Calculations
76
The transmission delay for the SEND(090) instruction can be calculated using
the following equation, which is illustrated in the following diagram.
Max. delay =Local node service cycle + local node service processing time +
transmission processing time + reception processing time + re-
mote node service cycle + remote node service processing time +
CPU data set processing time (remote node)
SEND(090) executed
in user program
CPU Bus Unit service processing time (local node)
Maximum transmission delay
The CPU Bus Unit service cycle is a single PC cycle.
This is the time required to process CPU Bus Units and is approximately 1 ms for
Ethernet Units.
Number of words transferred x 0.011 + 3 ms
Number of words transferred x 0.011 + 3 ms
Number of words transferred x 0.02 + 20 ms
Note 1. The actual operating environment can cause transmission delays larger
than those calculated with the methods given here. Among the causes of
longer delays are the following: traffic on the network, window sizes at net-
work nodes, traffic through the Ethernet Unit (e.g., socket servicing, FTP
server communications, etc.), and the system configuration.
2. The CPU data set processing time is the standard when the peripheral ser-
vice time is set in the CPU Unit System Setup to the default of 4%. As this
value is increased, the processing time is shortened.
The following example shows calculations for sending 256 words between two
PC nodes using SEND(090). The local node's CPU cycle time is 10 ms, and the
remote node's CPU cycle time is 5 ms. Calculations are shown in the following
table.
CPU Bus Unit service cycle (local node)
CPU Bus Unit service processing time (local
node)
Transmission processing time
Reception processing time
CPU Bus Unit service cycle (remote node)
CPU Bus Unit service processing time
(remote node)
CPU data set processing time (remote node)
Total
CPU Bus Unit service cycle (local node)
Transmission processing time
Reception processing time
CPU Bus Unit service cycle (remote node)
CPU Bus Unit service processing time (remote node)
CPU data set processing time (remote node)
Item
Section
Calculation
PC cycle time = 10 ms
1 ms
256 x 0.011 + 3 = 5.816
256 x 0.011 + 3 = 5.816
5 ms
1 ms
256 x 0.02 + 20 = 25.12
10 + 1 +6 + 6 + 5 + 1 + 25= 54 ms
5-3
6 ms
6 ms
25 ms