Mitsubishi plc user manual / hand book
FX-2DA for Mitsubishi FX PLC
Digital to analog converter
The FX-2DA analog special function block has two output channels. The output channels take a digital value
and output an equivalent analog signal. This is called a D/A conversion. The FX-2DA has a maximum
resolution of 12 bits.
** The selection of voltage or current based input/output is by user wiring. Analog ranges of -10 to 10V
(resolution: 5mV), and/or 4 to 20mA (resolution: 20mA) maybe selected.
** FX programmable controllers versions 2.0 or later (those with serial number 13XXXX or larger) are
required; as these units have the TO/FROM applied instructions in their instruction set. Data transfer
between the FX-2DA and the FX base unit is by buffer memory exchange. There are 32 buffer memories
(each of 16 bits) in the FX-2DA.
** The FX-2DA occupies 8 points of I/O on the FX, FX2C expansion bus. The 8 points can be allocated from
either inputs or outputs. The FX-2DA draws 30mA from the 5V rail of the base unit or powered extension
*** Channel Selection
Switching between voltage and current output modes. The value of BFM #0 switches the analog output
between voltage and current on channels CH1 and CH2. It takes the form of a 2-character HEX number.
The least significant character controls CH1 and the other controls CH2.
Control of each O HEX character of HOO
O=0 Voltage output (-10V to +10V) O=1 Current output (+4mA to +20mA)
Example : H10 CH1 : Voltage output CH2 Current output
*** Last data reset
If the programmable controller is changed to the STOP state, the FX-2DA will continue to output the last
value. To reset the output to the offset value, set the HEX characters of BFM #5 to one of the appropriate
H01 : CH2=Hold, CH1=Reset
H10 : CH2=Reset, CH1=Hold
H11 : CH2=Reset, CH1=Reset
Both channels are held when BFM #5 = H00.
*** Digital to Analog conversion speed change
By writing 0 or 1 into BFM #7 of the FX-2DA, the speed at which D-A conversion is performed can be
changed. However the following points should be noted:
Note : lThe conversion speed does not depend on the number of channels being used.
lOn power up, the FX-2DA is set for normal speed conversion and BFM #7 contains 0.
(4) Adjusting Gain and Offset Values
When BFM #20 is set to K1, all settings in the buffer memory are reset to their default settings. This
allows the buffer memory settings to be set from the beginning again when many settings have
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