Mitsubishi Electric FX3U-232-BD User Manual page 321

FX Series PLC User's Manual - Data Communication Edition
Computer Link
2. When ch2 is used in FX
Device
On-demand send
M8427
processing
M8428 On-demand error flag
On-demand byte/word
M8429
changeover
On-demand head device
D8427
number specification
On-demand data quantity
D8428
specification
Point
• The on-demand send processing signal (M8127 or M8427) turns ON when the PLC gives a request to
send data to the computer, and turns OFF when sending of the specified data is completed. Use this signal
for interlock to prevent giving two or more on-demand requests at the same time.
• While the on-demand send processing signal is ON, the PLC cannot receive commands sent from the
computer.
• Amount of on-demand data and number of data registers used for sending according to the unit
specification (word or byte)
When the specified unit is a word:
The amount of on-demand data is equivalent to the number of data registers to be sent.
When the specified unit is a byte:
Two on-demand data units use one data register for sending.
Example: When the amount of on-demand data is "5", the number of data registers for sending is "3".
, FX , FX and FX
3G 3GC 3U
Name
Remains ON while the on-demand function is being executed.
ON: On-demand data is being sent.
OFF: Sending of on-demand data is completed.
Turns ON when an error is included in a specified value to be sent in the on-
demand function.
ON: Error is included.
OFF: Error is not included.
Specifies the unit (byte or word) of data handled in the on-demand function.
ON: Unit = Byte (8-bit)
OFF: Unit = Word (16-bit)
Sets the head data register device number containing the data to be sent
using the on-demand function in a sequence program.
Sets the amount of data to be sent using the on-demand function in a
sequence program.
PLCs
3UC
Description
7 Commands
7.13 On-demand Function
A
B
C
D
E
F
G
H
I
Apx.A
D-79