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Sending Commands From a PC Section 5-3
RECV(098)
The transmission delay for the RECV(098) 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 (command) + reception pro-
cessing time (command) + remote node service cycle + remote
node service processing time + CPU data read processing
time (remote node) + remote node service processing time +
transmission processing time (response) + reception process-
ing time (response) + local node service cycle + local node ser-
vice processing time + CPU data set processing time (local
node)
CPU Bus Unit Service
Cycle
The CPU Bus Unit service cycle is a single PC cycle.
CPU Bus Unit Service
Processing Time
This is the time required to process CPU Bus Units and is approximately 1 ms
for Ethernet Units.
Transmission and
Reception Processing
Times
Command: 3 ms
Response: Number of words transferred x 0.011 + 3 ms
CPU Data Read
Processing Time
The CPU data read processing time is the integer portion of the minimum
cycle time, which satisfies the following formula.
Number of words transferred x 0.02 + 20 ms
≤ Integer portion of remote node
cycle time
CPU Data Set Processing
Time
Number of words transferred x 0.02 + 20 ms
Item Calculation
CPU Bus Unit service cycle (local node) PC cycle time = 10 ms
CPU Bus Unit service processing time (local
node)
1 ms
Transmission processing time 256 x 0.011 + 3 = 5.816 ≅ 6 ms
Reception processing time 256 x 0.011 + 3 = 5.816 ≅ 6 ms
CPU Bus Unit service cycle (remote node) 5 ms
CPU Bus Unit service processing time (remote
node)
1 ms
CPU data set processing time (remote node) 256 x 0.02 + 20 = 25.12 ≅ 25 ms
Total 10 + 1 +6 + 6 + 5 + 1 + 25= 54 ms
RECV(098) executed in user program
CPU Bus Unit service
processing time (local node)
Transmission processing time (com-
mand)
Reception processing time
(command)
CPU Bus Unit service cycle (remote node)
CPU Bus Unit service processing time (remote node)
CPU Bus Unit service processing time (local node)
Reception processing time (response)
Transmission processing time (response)
CPU data set processing time
Service processing
Service processing
Maximum transmission delay