Logic Configuration - ABB SM2000 User Manual Supplement

3 LOGIC CONFIGURATION

3.1 Logic Equation Description
Note.
• 12 logic equations
• Up to 6 operands and 5 operators per equation
• OR/AND/NOR/XOR/NAND/NOT operators – see
Table 3.1 overleaf
• Can combine internal and external digital signals
– i.e. alarms, digital inputs, other logic equation
results and real time events (timer option).
Control
Valve
Alarm 1.1B
Alarm 1.1A
80
50
feet
feet
Flow Conditions
Close reservoir control valve if:
• Reservoir level >50 feet AND rate of change >10 ft/hr
OR
• Reservoir level >80 ft
OR
• Manual override switch operated
Alarm 1.1A
And
Alarm 1.2A
Alarm 1.1B
Digital i/p C1
Relay Output
Or
Equation
1
Or
result
Note. Elements on each equation are calculated sequentially.
Fig. 3.1 Logic Equation Example
3.2 Worked Example – Reservoir Level Control
– Fig. 3.1
Note. This example uses an optional Hybrid I/O Module
in position C – see Appendix 5.
• Channel 1.1 records the reservoir level, with an
engineering range 0 to 100 feet.
• Alarms 1.1A, 1.1B and 1.2A monitor the reservoir
level.
• Digital output C6 to drive the control valve from
Logic Equation 1
• Digital input C1 to operate the manual override.
Manual Overide
Alarm 1.2A
Level Sensor
Input Elements
• Alarm 1.1A – set to high process trip at 50 ft
• Alarm 1.1B – set to high process trip at 80 ft
• Alarm 1.2A – set to fast rate trip at 10% of range per hour
(10 ft/hr)
• Manual override switch:
Connected to (optional) digital input B1
Group 1 Configuration
Eqn 1
Eqn2 Eqn3
Operand/Operator 1
Operand/Operator 2
Operand/Operator 3
Operand/Operator 4
Log Enable & Eqn Tag
Rate of
change
Level
> 3m/h
Time
--->
Eqn4 Eqn5 Eqn6
Alarm State 1.1A and
Alarm State 1.2A or Digital i/p D6, None
Alarm State 1.1B or
Digital i/p D6, None
Digital i/p C1, End
Inlet Head Calculation
15