ABB COMMANDER 1900 Series Programming Manual page 28

...4 ADVANCED CONFIGURATION LEVEL
4.2 Set Up Logic
Information.
• 4 logic equations
• 7 elements per equation
• OR/AND operators
• Can combine internal and external digital signals – i.e. alarms, digital inputs, other logic equation results and real time
events (timer option).
For each equation, the logic elements 1 to 7 are arranged sequentially, as shown below. Odd numbered elements are used for
logic inputs and even numbered elements for logic gates.
Logic inputs must be set to one of the digital sources listed in Table 3.1 on page 15.
Logic gates must be set to ANd, Oror End. Setting an element to End terminates the equation.
EQN1. 2
EQN1. 1
EQN1. 3
ANd/Or
Logic
Inputs
EQN1. 5
EQN1. 7
Example – Reservoir level monitoring using:
• process variable 1 with an engineering range 0 to 100 feet
• logic equation 1 result assigned to relay 1.1 which is used to operate the control valve.
Control
Valve
Alarm B1
Alarm A1
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
26
EQN1. 4
EQN1. 6
ANd/Or
Result
ANd/Or
Manual Overide
Relay Output
Level Sensor
Input Elements
• Alarm A1 – set to high process trip at 50 ft
• Alarm B1 – set to high process trip at 80 ft
• Alarm C1 – set to fast rate trip at 10% of
range per hour (10 ft/hr)
• Manual override switch:
Connected to digital input 1.1
Digital input number
Module number
Negative polarity
Volt-free switching
Note. Elements on each equation are calculated
sequentially, i.e. elements 1, 2 and 3 are evaluated first and
this result is then combined with elements 4 and 5. Similarly,
this resultant is then combined with elements 6 and 7 to give
the logic equation result.
Entering the Logic Equation
EQN1. 1
AL–A1
AL–C1
EQN1. 3
AL–B1
EQN1. 5
dIG–1. 1
EQN1. 7
Rate of
change
Level
> 10ft/h/
Time
Alarm C1
EQN1. 2
ANd
EQN1. 4
Or
EQN1. 6
Or