Bfm#28: Over-Scale Status - Mitsubishi Electric FX3G User Manual

FX /FX /FX /FX /FX
3S 3G 3GC 3U 3UC
FX -4AD/FX -4AD (4-channel Analog Input)
3U 3UC

5.4.11 BFM#28: Over-scale status

If the input analog value is out of the A/D conversion range, the following operation will be performed:
• If "(analog input value) < (lower limit value in A/D conversion range)":
The over-scale lower limit bit will turn on.
• If "(analog input value) < (upper limit value in A/D conversion range)":
The over-scale upper limit bit will turn on.
1. A/D conversion range
Input type
Voltage input
Current input
2. Assignment of each bit of BFM#28
Bit No. Channel number
b0
b1
b2
b3
b4
b5
b6
b7
b8 to b15
3. Caution regarding use of over-scale status data
• Perform one of the following operations to turn off the previously turned on bit:
- Turn the power off and on.
- Write "H0000" in BFM#28 as the over-scale status data.
• Even if over scale is detected, channel data (BFM#10 to #13) will continuously be updated.
• The over-scale status data automatic transfer function is not supported when connected and used with the
FX5U or FX5UC CPU module.
4. Over-scale status data automatic transfer function (b7 of BFM#22)
If the over-scale status data automatic transfer-to data register is specified in BFM#128, the data in BFM#28
can be transferred to the specified data register.
When over-scale is detected, data will be automatically transferred from the 4AD to the PLC. For this reason,
the PLC does not need any program for reading the data, and the scan time of the PLC can be shortened.
Convenient function
setting
ON = Valid
BFM#22 b7:ON
PLC User's Manual - Analog Control Edition
A/D conversion range
-10.2V to +10.2V
-20.4mA to +20.4mA
ch1
ch2
ch3
ch4
Not used.
Transfer-from memory
BFM#28
Numeric data type: Hexadecimal (H)
Description
Over-scale (lower limit)
Over-scale (upper limit)
Over-scale (lower limit)
Over-scale (upper limit)
Over-scale (lower limit)
Over-scale (upper limit)
Over-scale (lower limit)
Over-scale (upper limit)
Automatic data transfer function
Transfer-to data register specification
→
5 Buffer Memory (BFM)
5.4 Buffer Memory Details
Initial value: H0000
 : Represents a numeric value.
(BFM#128: K  )
D 
B-35
A
B
C
D
E
F
G
H
I
J