Mitsubishi Electric FX3G User Manual page 344

FX /FX /FX /FX /FX
3S 3G 3GC 3U
FX -3A-ADP (2-channel Analog Input, 1-channel Analog Output)
3U
2.4.2 When connected to a FX
1. Conversion and special data register update timing
A/D and D/A conversion is performed at every scan time of the PLC.
During execution of END instruction, the PLC performs A/D conversion, reads out the A/D converted data,
and then writes the data in the special data registers.
The PLC writes output setting data to special data registers, performs D/A conversion, and updates analog
output values.
FX -3A-ADP
3U
2nd
A/D conversion
90 s for each
selected input
channel
D/A conversion
50 s for each
selected output
channel
2. Conversion during PLC STOP
1) A/D conversion
Even if the PLC is stopped, A/D conversion will be performed and the special data registers will be
updated.
2) D/A conversion
If the output holding function cancellation setting is enabled by the special device, the offset value will be
output.
If the output holding function cancellation setting is disabled, the output at switching from RUN to STOP
will be latched.
Just after power-on, however, the offset value will be output until operation begins.
3. If two or more analog special adapters are connected
1) A/D conversion
During execution of the END instruction, data will be read out from all the connected adapters (in the
order of 1st adapter → 2nd adapter).
2) D/A conversion
During execution of the END instruction, data in all the connected adapters will be subject to D/A
conversion and then output (in the order of 1st adapter → 2nd adapter).
4. Conversion speed (data update time)
1) A/D conversion
During execution of END instruction, the A/D converted data of "90 μs for each selected input channel",
and the data read out will be written to the special data registers.
END instruction execution time will be "90 μs for each selected input channel × number of connected
analog adapters."
2) D/A conversion
During execution of END instruction, the output setting digital data per of "50 μs for each selected output
channel", after which the analog data will be output.
END instruction execution time will be "50 μs for each selected output channel × number of connected
adapters."
H-10
PLC User's Manual - Analog Control Edition
3UC
/FX
3G 3GC
FX
3U
A/D conversion
90 s for each
selected input
channel
D/A conversion
50 s for each
selected output
channel
+
PLC
-3A-ADP
1st
A/D,D/A conversion
start command
Digital value writing
+
Digital value reading
A/D,D/A conversion
start command
Digital value writing
Digital value reading
2 Specifications
2.4 Conversion Time
FX /FX Series PLC
3G 3GC
Sequence
program
End instruction