Current Input Characteristics - Mitsubishi Electric MELSEC A Series Manual

3. SPECIFICATIONS
3.3.2

Current input characteristics

1/4000
setting
4095
2000
Digital
output
value
0
-2000
-4096
Setting Offset
Example No. Value
1 0 mA
2 4 mA
3 0 mA
Figure 3.3 shows the voltage input characteristics for three different offset/gain
combinations
1/8000 1/12000
setting setting
8191 12287
4000 6000
0 0
-4000 -6000
-8192 -12288
Digital Output Value with +7 mA
Gain
value
1/4000
Setting
5 mA 2800
20 mA 374
20 mA 700
Figure 3.3 Current Input Characteristics
POINTS
(1) When the input voltage is in the range from -20 to 0 to +20 mA , the maxi-
mum resolution and overall accuracy are within the range of performance
specifications. However, if input current exceeds this range, resolution and
accuracy will be impaired
(2) Inputting an analog current that causes the digital output value to exceed
the maximum value (4095/8191/12287) or to become smaller than the
minimum value (-4096/-8192/-12288), locks the result of the A-D conver-
sion (digital output value) at either the maximum value (4095/8191/12287)
or the minimum value (-4096/8192/-12288).
(3) Do not apply ± 30 mA or more. This will damage the module.
(4) When setting the gain or offset, the following must be satisfied:
(Gain value) – (Offset value) ≥ 4 mA (1/4000 setting)/6 mA (1/8000
setting)/8 mA (1/12000 setting)
If the set values do not satisfy the relationship stated above, the obtained
digital output values will not be correct.
Practical analog input range
-30 -20 0
Analog input voltage (V)
Analog Input
1/8000 1/12000
Setting Setting
5600 8400
748 1122
1400 2100
3 − 5
Setting example [1]
Offset value: 0 mA
Gain value:
Setting example [2]
Offset value: 4 mA
Gain value:
4
Setting example [3]
Offset value: 0 mA
Gain value: 20 mA
20 30
Digital Output Value with -3 mA
Analog Input
1/4000 1/8000
Setting Setting
-1200 -2400
-874 -1748
-300 -600
MELSEC-A
5 mA
20 mA
1/12000
Setting
-3600
-2622
-900