SCADA Applications
Real time control
Pertaining to the performance of a computation
during the actual time that the related
physical process transpires.
SCADA: refer to the response of the control
system to changes in the process.
• Example
Bases on the preceding discussion calculate a scan interval for a SCADA
system:
1. 3 RTUs but will likely increase eventually to 10. Number RTU equal
10.
2. The largest RTU has the following point counts: 100 status points, 10
alarm points, 10 measurement meter(16bits each), 10 analog
points (16bits each)
3.MTU send the following point counts to RTU: 150 discrete
control(valve motor) points, 5 stepping motor positions(16bits
each), 20 valve controller set points (16bits each).
4. Data rate is based on the UHF radio send for communication. Used
1200bps.
5. Communication efficiency 60%
solutions
• 100+10+160+160+150+80+320=980
• 10x980=10000 bits to move at data rate
1200bits /s
• 10000/1200=9s for 100% efficiency
• For 60%, 9s/0.6=15s
• Its good to used delay 15s -30s.
Example 2: A 12 bit binary absolute encoder is outputting
the number 1011010101112
• i) A 12 bit encoder will output 212 binary
numbers for one revolution. Therefore the
resolution is 360 degrees / 212 = 0.087891
degree.
• ii) Converting the binary number to decimal,
we have 1011000101112 = 283910. The
indicated angle is between 2839 x 0.087891 =
249.52 degrees and 249.52 + 0.087891 =
249.60 degrees.