Control Procedures And Setting Methods - Mitsubishi FX3U-USB-BD User Manual

FX Series PLC User's Manual - Data Communication Edition
Computer Link
6.

Control Procedures and Setting Methods

6.1 Data Flow by Link
The figures below show images of data flow achieved when data is read from or written to a PLC CPU and
the status is controlled.
In the case of communication in accordance with RS-232C, ignore "485PC-IF" and regard "485ADP" as
"232ADP".
1. When the computer reads data from the PLC
Computer
OS *1
[10] [11]
2. When the computer writes data to the PLC
Computer
OS *1
3. When the PLC sends data to the computer (on-demand function)
Computer
OS *1
Write
*1. The OS (standing for "Operating System") indicates the software used to efficiently operate the
resources including the CPUs, memories, terminals, files, and networks using user programs, etc.
D-42
485PC-IF
RS-232C
[2] Command
[9] Various data
[12] Response
Device
memory
information
Interface for
(read)
signal
PLC CPU
conversion
information
(read)
RS-232C
485PC-IF
[2] Command,
data, etc.
[8] Response
Device
memory
information
(written)
PLC CPU
information
(written)
485PC-IF
RS-232C
[6] Data
On-demand
data
[7]
485ADP
RS-485
[3]
[8]
[13] [14]
485ADP
RS-485
[3]
[7]
485ADP
RS-485
[4] Data
[5]
6 Control Procedures and Setting Methods
6.1 Data Flow by Link
PLC CPU
[4]
[7]
Sequence
*1
OS
[5] Read
[6] Data
Device
memory, etc.
PLC CPU
[4]
Sequence
OS *1
[6]
[5] Write
Device
memory, etc.
PLC CPU
Sequence
*1
OS
[2]
[3] Data [1] Sending
Read
Device
memory, etc.
Data writing
program
program
program
request
+