178
R E F P
D
n
FNC
50
1
2
M
3
○○○○
n
X Y M S
D.b R.b
KnX KnY
KnM KnS
T C
D,R
V,Z
UnG
K,H
E
" $"
D
D : the head address of I/O device to be refreshed
n : the number of I/O devices to be refreshed
Since the PLC is by the Cyclic Operation, the CPU will read and store "ON"/ "OFF" status of all external inputs to its
input data memory once at the beginning of the user program (every time when the PLC processes the step 0).
Then until the END instruction is executed, all the “ON”/ “OFF” status in its output data memory will be sent to
output components to drive external loadings. However, when there is a need to read “ON”/ “OFF” status of the
input X during the execution of the program or to deliver the operation result to the output Y immediately, please
use this REF instruction.
Refresh input signals to the input data memory
Deliver the output data memory to output components
REF X0 K8
REF Y0 K8
M0
M1
REF X0 K8
M0
n
D
D
n
Operand
Devices
I/O Refresh
The D should designate as X0, X10 or Y0 When D=X0, n=8 or 16. When D = X10 or Y0, n = 8.
When M0=“ON”, the input signal statuses of X0~X7 will be reloaded to PLC’s status data memory. The PLC can
immediately read the external statuses of X0~ X7 while performing this instruction, but there is still an approximately
10ms input delay on the input circuit and lter.
When M1=“ON”, the output statuses of Y0~Y7 will be sent to the output components from the PLC’s status data
memory. Therefor PLC can immediately send the statuses of Y0~Y7 while performing this instruction, but there still
has some delay on the output components ((e.g., relay has10ms delay approximately).
Usually use the REF instruction in interrupt subroutines to acquire real-time input/output statuses.
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