 We
like to recommend the combination use of 2-input Math Function Module
(Model: JF) and a DC Input Digital Panel Meter (Model: 46DL).
As for this time request, please specify the JF’s equation as Subtraction
(suffix code as /3 ). And for each parameter, please specify the gain
K1 as 0.5, the gain K2 as -0.5 and the bias A0 as +50%. The K1 is gain
of input 1 (= inside gate value), the K2 is gain of input 2 (= outside
gate value).
By the above parameter setting, the JF unit will output 12 mA when there
is no water-level difference between inside gate and outside gate. As
for each input/output relation, please refer followings,
| Example
1 |
 |
Input 1: 12 mA (50%)
Input 2: 12 mA (50%)
Output: 12 mA (50%) |
| Output = (K1 x input 1) + (K2 x input 2) + A0 |
|
|
= (0.5 x 0.5) + (-0.5 x 0.5)
+ 0.5
= 0.25 – 0.25 + 0.5
= 0.5 (= 50% = 12 mA) |
| Example
2 |
|
Input 1: 20 mA (100%)
Input 2: 4 mA (0%)
Output: 20 mA (100%) |
| Output = (K1 x input 1) + (K2 x input 2) + A0 |
|
|
= (0.5 x 1) + (-0.5 x 0)
+ 0.5
= 0.5 – 0 + 0.5
= 1 (= 100% = 20 mA) |
|
|
| Example
3 |
|
Input 1: 4 mA (0%)
Input 2: 20 mA (100%)
Output: 4 mA (0%) |
| Output = (K1 x input 1) + (K2 x input 2) +
A0 |
|
|
= (0.5 x 0) + (-0.5 x 1) + 0.5
= 0 – 0.5 + 0.5
= 0 (= 0% = 4 mA) |
|
| When you specify the scaling for the digital panel
meter, 46DL as -5.00 m to +5.00 m corresponding to the 4-20 mA signal
from the JF unit then you can see the display value as requested. |
|
We
plan to measure water levels of inside and outside of water gate by water-level
gauge. We’d like to display the water level difference between the
two gauges. On the panel, we like to display them as follows: