Sample Programs When The A68Adn Is Loaded Onto Remote I/O Station - Mitsubishi Electric MELSEC A Series Manual

5. PROGRAMMING
5.2

Sample programs when the A68ADN is loaded onto remote I/O station

[Precautions when writing programs]
(1) Data transmission/receive method
Data transmission/receive is made in the batch refresh mode after executing an
END (FEND) instruction, even though the PC CPU I/O control mode is direct or
refresh.
(2) Response delay
When transmitting/receiving control information between a master station P
CPU and an A68ADN in a remote I/O station, a response delay is inevitable
because control is made through a link module.
Pay attention to control timing.
(3) User instructions
The following instructions are used for data transmission/receive between a
master station PC CPU and an A68ADN in a remote I/O station.
(a) Data write (master station → A68ADN): RTOP
(b) Data read (A68ADN → master station): RFRP
(4) Data transmission/receive device
Use link registers (W) for data transmission/receive between a master station
PC CPU and an A68ADN in a remote I/O station.
Install the following program to the master station as needed:
(a) When writing data:
Transmit the data that is to be sent to the the remote I/O station A68ADN to
the designated link register before executing an RTOP instruction.
(b) When reading data:
Transmit the link register data to another device before executing an RFRP
instruction.
(5) Simultaneous execution of RTOP and RFRP instructions is not possible:
Simultaneous execution of an RTOP instruction and an RFRP instruction at the
same time for the same A68ADN cannot be done.
signal must be added to the program as an interlock condition.
However, if two A68ADN modules are loaded in a remote I/O station, it is possi-
ble to execute an RTOP instruction for one A68ADN and an RFRP instruction
for the other module at the same time.
5 − 3
MELSEC-A
Therefore, the data link I/O