Panasonic AFP7CCM1, Руководство пользователя

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8.4 MODBUS RTU Master Communication (SEND)
8-9
8.4 MODBUS RTU Master Communication (SEND)
8.4.1 Write Data into an External Device

Instructions
In master communication, PLC has the sending right, and executes communication by
sending commands to devices that support MODBUS-RTU, and receiving responses.
Messages in accordance with the protocol are automatically generated by PLC. In the user
program, reading and writing can be done simply by specifying the station no. and memory
address and executing SEND/RECV instructions.
External device
supporting Modbus-RTU
(Hex) 01 10 00 00 00 02 04 00 64 00 00 (CRC)
(Hex) 01 10 00 00 00 02 (CRC)
Command message
Response message
DT100 100
DT101 0
・・・・・・ ・・・・・・・・
・・・・・・ ・・・・・・・・
40001 100
40002 0
・・・・・・ ・・・・・・・・
・・・・・・ ・・・・・・・・
PLC
Specify and write station no. and address based on SEND instruction

Sample program

Send commands from the COM1 port of the CPU unit, and write the content of PLC's data
register DT100 - DT101 into the data area of an external device (station no. 1) 40001 - 40002.

Confirm that the unit is in the master mode (XC), and that the sending process is not in
progress for the same port (YC), and start up the SEND instruction.

In the UNITSEL instruction, specify the slot No. (U0) and the COM. port No. (U1).

In the SEND instruction, specify and execute the PLC initial address (DT100), No. of data
(U2), MODBUS function code to be used (16: H10), partner device station no. (H01), and
initial address (H0). For the address of the partner device, please check operating
instructions, etc. of the relevant device.
R0
R100
UNITSEL U0 U1
SEND.US DT0 H1001 H0 DT100 U2
R100
Execute
SEND
Settings for communication port
S1: Slot 0 (U0)
S2: COM1 (U1)
SEND execution conditions
Clear to send flag: ON
Sending active flag: OFF
SEND process
S: Data saving area (DT100)
n: No. of sent data (U2)
D1: MODBUS code (H10) and
partner device station no. (H01)
D2: "Transmit to" address (H0)
D3: Execution result code (DT0)
Master
communication
Clear to send flag
XC YC
Master
communication
Sending active flag
（ ）
DF
S1 S2
S n D1 D2 D3
(Note 1) Operand [S1] of SEND instruction is specified by combining two hexadecimal digits of MODBUS function
code with two hexadecimal digits of partner device station no. When the MODBUS function code is 16, specify
H10 for [D1].
(Note 2) When the partner device is FP series PLC, Operand [S2] of SEND instruction can be specified using the
Device No.
(Note 3) The unit number and COM port number in the above program is applied when the COM.1 port of the CPU
unit is used.
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