3. SPECIFICATIONS
3
−
8
MELSEC-A
(7)
Unit ready: XnF
This signal indicates whether the unit is able to operate.
It turns ON automatically when unit operation is enabled.
3.4 Buffer Memory
Buffer data is used for data communication between DN91 and the PLC CPU.
It is used for reading and writing of DN91 buffer memory data and for the PLC CPU FROM/TO
instructions.
The buffer memory returns to zero (0) when powered OFF or when the PLC CPU reset.
If the parameters are set by the sequence program, however, the "Parameter" area is
initialized with the parameters that are already set.
3.4.1 Buffer memory table
The buffer memory table is shown in Table 3.4.
Table 3.4 Buffer Memory Table
Address
Hexadecimal
Decimal
Item
Contents
Write Enabled/
Disabled by CPU
See
Page
0000
H
to 007F
H
0 to 127
Input data
Stores input data from each slave station.
Disabled
3.4.2 (1)
0080
H
to 00FF
H
128 to 255 Output data
Stores output data for each slave station.
Enabled
3.4.2 (2)
0100
H
to 010F
H
256 to 271 Not used
0110
H
to 011F
H
272 to 287
Message communication
command
Stores request data for message
communication.
Enabled
3.4.2 (3)
0120
H
to 012F
H
288 to 303
Message communication
result
Stores result data from message
communication.
Disabled
3.4.2 (4)
0130
H
to 01A7
H
304 to 423
Message communication
data
Stores communication data for message
communication.
Enabled
3.4.2 (5)
01A8
H
to 01A9
H
424 to 425 Model display
Setting is "DN91" in ASCII code
Disabled
01AA
H
to 01AF
H
426 to 431 Not used
01B0
H
432
Master communication
status
Stores the DN91 status
Disabled
3.4.2 (6)
01B1
H
433
Error information
Upper byte: Error code
Lower byte: Stores station number where the
error occurred.
Disabled
3.4.2 (7)
01B2
H
434
Bus error counter
Stores the number of error detections for
communication data.
Disabled
3.4.2 (8)
01B3
H
435
Bus-off counter
Stores the number of communication errors.
Disabled
3.4.2 (9)
01B4
H
to 01B7
H
436 to 439
Configuration status of
each station
Indicates whether parameters are set for
each slave station.
Disabled
3.4.2 (10)
01B8
H
to 01BB
H
440 to 443 Not used
01BC
H
to 01BF
H
444 to 447
Communication status of
each station
Indicates whether each station is conducting
I/O communication
Disabled
3.4.2 (11)
01C0
H
to 01C3
H
448 to 451 Not used
01C4
H
to 01C7
H
452 to 455
Error status of each
station
Indicates whether an error has occurred for
each station.
Disabled
3.4.2 (12)
01C8
H
to 01CB
H
456 to 459 Not used
01CC
H
to 01CF
H
460 to 463
Down-station detection
disabled setting
Sets whether a down slave station is
reflected in the slave down signal (Xn4).
Disabled
3.4.2 (13)
01D0
H
to 01D3
H
464 to 467 Not used
01D4
H
to 03CF
H
468 to 975 Parameter
Area to set parameters with a sequence
program.
Enabled
3.4.2 (14)
