WD3A and RD3A instructions in the PLC

WR3A/RD3A: The FX1N and FX2N PLCs only support these two commands, the module name FX0N-3A, but make it read-only using the FX0N FROM / TO instruction.

WR3A: special function module write instruction;

K0: Module number:

K1: Analog input channel K1 or K2 (physical interface number); D15: Meaning of the analog module to write the specified value: Write D15 value? 0N3A module D / A;

The D / A physical interface has only K1 unchanged values;

For example: LDX1 WR3A K0 K1 D15 is closed, when the analogy of X1's D15 value is output to analog output channel 1;


Example of reading slave data instruction: RD3AK1 H0 D0

The RD3A was originally an analog module read command, and the original command function could not be used.

The RD3A instruction corresponds to the Modbus 03 function and reads the (4X type) register.

In the instruction, K1 is the station number representing the slave device being read, the range is 1-247; H0 is the address number 0000 (indicated by the hexadecimal number) representing the data to be read in the slave device;

The value in D0 is the number of registers that are read, the range is 1-32, and the read data is stored in D1, D2, and D3 in sequence.

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