Mitsubishi Electronics MELSEC-F Manuel D’Utilisation
E-31
5 Buffer Memory (BFM)
5.4 Buffer Memory Details
A
Comm
on I
te
te
ms
B
FX
3U
-4AD
FX
3UC
-4
A
D
C
FX
3U
-4A
D
D
-A
D
P
D
FX
3G
-2A
D
D
-BD
E
FX
3U
-4DA
F
FX
3U
-4D
A
A
-AD
P
P
G
FX
3G
-1D
A
A
-BD
H
FX
3U
-3
A-
ADP
I
FX
3U
-4
A
D
-P
T
-
A
D
P
J
FX
3U
-4A
D
D
-P
TW
-
A
A
D
P
FX
3G
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
FX
3U
-4DA (4-channel Analog Output)
5.4.14 BFM #39: Upper/lower limit function status
Initial value: H0000
Numeric data type: Hexadecimal (H)
When any of the output data (BFM #1 to #4) is out of range between the lower limit and the upper limit (BFM
#41 to #48), the relevant bit is turned on.
#41 to #48), the relevant bit is turned on.
1. Assignment to each bit of BFM #39
2. Cautions regarding use of the upper/lower limit function status
• The ON bits of the upper/lower limit function status are latched after the output data has returned to the
specified ranges between the upper and lower limits.
• The upper/lower limit function status can be reset by the following methods.
- Use the upper/lower limit function status reset function (BFM #40).
- Turn the power supply off then on.
- Turn the power supply off then on.
3. Upper/lower limit automatic transfer function (b1 of BFM #60)
If the upper/lower limit automatic transfer data register is specified in BFM #62, the data in BFM #39 can be
transferred to a specified data register.
Only when an error is detected, data will be automatically transferred from the FX
transferred to a specified data register.
Only when an error is detected, data will be automatically transferred from the FX
3U
-4DA to the PLC. For this
reason, the PLC does not need the program for reading data, and the scan time of the PLC can be shortened.
→ For a detailed description of the status automatic transfer function, refer to Subsection 5.4.18.
5.4.15 BFM #40: Clearance of upper/lower limit function status
Initial value: H0000
Numeric data type: Hexadecimal (H)
The flags can be reset by turning on the following bits of BFM #40.
1. Assignment to each bit of BFM #40
2. Operation to be performed after resetting
At the completion of status reset, the bits of BFM #40 will automatically turn off.
Bit
Description
b0
Data output from channel 1 < Lower limit (BFM #41)
b1
Data output from channel 1 > Upper limit (BFM #45)
b2
Data output from channel 2 < Lower limit (BFM #42)
b3
Data output from channel 2 > Upper limit (BFM #46)
b4
Data output from channel 3 < Lower limit (BFM #43)
b5
Data output from channel 3 > Upper limit (BFM #47)
b6
Data output from channel 4 < Lower limit (BFM #44)
b7
Data output from channel 4 > Upper limit (BFM #48)
b8 to b15
Not used
Bit
Description
b0
Clearance of lower limit status
b1
Clearance of upper limit status
b2 to b15
Invalid