4-5
Section
Analog Input Functions
85
In the following example, the peak value function is in effect for input number 1,
and the unit number is 0.
10004
Input condition
The maximum
conversion
data value is
held for input
number 1.
When mean value processing is used together with the peak value function, the
mean value will be held.
As long as the peak value function is in effect, the peak value will be held even in
the event of a disconnection.
4-5-5 Input Disconnection Detection Function
When an input signal range of 1 to 5 V (4 to 20 mA) is used, input circuit discon-
nections can be detected. The detection conditions for each of the input signal
ranges are shown in the following table.
Range
Current/voltage
1 to 5 V
0.3 V max.
4 to 20 mA
1.2 mA max.
The input disconnection detection signals for each input number are stored in
bits 04 and 05 of IR word n+9. Specify these bits as execution conditions in order
to use disconnection detection in the user’s program.
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
Bit
Input 2
Input 1
Word n+9
The respective bit turns ON when a
disconnection is detected for a given
input. When the disconnection is
restored, the bit turns OFF.
For the IR word addresses, n = 100 + 10 x unit number.
For Units #A to #F (10 to 15), n = 400 + 10 x (unit number – 10).
The conversion value during a disconnection will be 0000.
Disconnection detection is performed on the input voltage/current data that has
been converted into digital values. Therefore, detected values may be different
from those shown in the above table due to offset and gain adjustments, etc.
In the following example, the conversion value is read only if there is no discon-
nection at analog input number 1. (The unit number is 0.)
MOV (21)
105
DM0001
10904
The conver-
sion value in
IR word 105
(input number
1) is read to
DM 00001.
