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Message Delay Times Section 8-4
Reception Processing
Number of words transferred × 0.00075 + 1.3 ms
Note The I/O response time can increase due to noise or restrictions on the number
of frames that can be transmitted while data links are operating.
Example
In this example, the maximum transmission delay is calculated for an instruc-
tion sending 256 words of data in a system with 32 nodes. Network specifics
are detailed below:
Baud rate: 2 Mbps
Max. node address: 32
Number of nodes: 32
Number of polled nodes per comm cycle: 4
Source node execution: Synchronous
Destination node execution: Asynchronous
Number of words: 256
Data link: Inactive
Note This communications cycle time is calculated assuming that there is no node
that transmits event frames before the SEND command is sent.
RECV Instruction
Maximum Delay Time
The data flow which will yield the maximum transfer interval from the time the
RECV(193)/RECV(98) instruction is executed by the user program to the time
the Controller Link Unit stores the data in the local Unit’s memory area is
described below.
Note Be sure to take into account the time required for data links and program exe-
cution, which are not included in the following example.
Link servicing interval (source node) PLC cycle time (source node)
Link service processing (source node) 1 ms
Transmission processing 0.00075 × 256 + 2 = 2.192 ≅
2.2 ms
Communications cycle time (See note.) 600 × 4 + 110 × 32 + 320 × 0 + 4 ×
0 + 2,290 = 8,210 µs ≅ 8.2 ms
Transmission delay 0.008 × 256 + 0.112 = 2.16 ≅
2.2 ms
Reception processing 0.00075 × 256 + 1.13 = 1.492 ≅
1.5 ms
Link servicing interval (destination node) As required by Programming
Device
Link service processing (destination node) 1 ms
Total (max. transmission delay) PLC cycle time (source node) +
Peripheral servicing interval
(destination node) + 16.1 ms