Mitsubishi L02CPU User Manual page 175

(c) Timing of write or read of the device data
The data of a bit device and a word device set for each setting No. are communicated in the END processing.
Even so, depending on the destination device for communications, data communications for one setting may
not be done completely, resulting in data inconsistency.
Destination device for
communications
Data of a bit device and a word device are
MELSEC-Q/L (Built-in
guaranteed to be communicated by setting
Ethernet Function)
unit.
MELSEC-Q/L (Ethernet
Data of a bit device are
Module)
guaranteed to be
communicated by setting
MELSEC-QnA
unit.
(Ethernet Module)
Within the setting range,
MELSEC-A (Ethernet
data of a bit device are
Module)
guaranteed to be
MELSEC-FX3 (Ethernet
communicated in units of
Block/ Adapter)
32 bits (2 words).
*1 If the COM instruction is used, the data are written or read not only in the END processing but also during sequence
scan (at the execution of the COM instruction).
*2 The order of the write and read is shown below.
• When "Write" is set for Communication Pattern: A word device comes first, then a bit device.
• When "Read" is set for Communication Pattern: A bit device comes first, then a word device.
• When "Transfer" is set for Communication Pattern: The host station reads the data of transmission source in
order of a bit device and a word device, and writes them to transmission destination in order of a word device and
a bit device.
*3 Because the write and read is performed from the data with smaller device number, use the device with the largest No.
to secure the data.
Device data
Bit device Word device
Data of a word
device are
guaranteed to be
communicated by
setting unit.
Within the setting
range, data of a
word device are
guaranteed to be
communicated in
units of 2 words.
CHAPTER 12 SIMPLE PLC COMMUNICATION FUNCTION
Data inconsistency for one setting
Data inconsistency of a bit device and a word device is the
same level because the data of both devices are communicated
at the same timing.
If both a bit device and a word device are set for the same
setting No., the level of data inconsistency of both devices may
be different because the data of each device is communicated
*2
at different timing.
• If both a bit device and a word device are set for the same
setting No., the level of data inconsistency of both devices
may be different because the data of each device is
communicated at different timing.
• If the data of 32 bits (2 words) or larger is communicated,
data inconsistency might differ in units of 32 bits (2 words).
*1
*2
*3
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