Mitsubishi Electronics MELSEC-F Manuel D’Utilisation
H-8
2 Specifications
2.4 Conversion Time
FX
3G
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
FX
3U
-3A-ADP (2-channel analog Input, 1-channel analog output)
2.4
Conversion Time
This section describes the conversion time.
2.4.1
When connected to a FX
3U
, FX
3UC
PLC
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.
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.
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.
updated.
2) D/A conversion
If the output holding function cancellation setting is disabled by the special device, the offset value will be
output.
If the output holding function cancellation setting is enabled, 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.
output.
If the output holding function cancellation setting is enabled, 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
order of 1st adapter
→ 2nd adapter... 4th 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
conversion and then output (in the order of 1st adapter
→ 2nd adapter... 4th adapter).
4. Conversion speed (data update time)
1) A/D conversion
During execution of END instruction, the A/D converted data of "80
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 "80
END instruction execution time will be "80
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 "40
μs for each selected output
channel", after which the analog data will be output.
END instruction execution time will be "40
END instruction execution time will be "40
μs for each selected output channel × number of connected
adapters."
n'th
1st
FX
3U
, FX
3UC
Series PLC
FX
3U
-3A-ADP
Sequence
program
End instruction
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
FX
3U
-3A-ADP
A/D conversion
80 s for each
selected input
channel
80 s for each
selected input
channel
μ
μ
+
D/A conversion
40 s for each
selected output
channel
40 s for each
selected output
channel
A/D conversion
80 s for each
selected input
channel
80 s for each
selected input
channel
μ
μ
+
D/A conversion
40 s for each
selected output
channel
40 s for each
selected output
channel