Industrial Data Systems IDS Scale Basic - Manual (Page 16)

Scale Basic 4.2E Tutorial
Setpoint Monitors
Purpose1: to monitor 2 registers and activate a scale basic function when the lower register is
greater than or equal to the upper register ( trigger when: lower register >= upper register ).
Purpose2: to monitor a condition code and activate a scale basic function when the condition is
true or false. Set the upper register to True or False then the lower register to a condition
code.
Remarks: Setpoint monitors are activated using the Scale Basic instruction: Setpoint On [x].
There are 16 setpoint monitor records that contain the following data:
Upper register [P0] the upper value register, setpoint triggers when lower >= upper
Lower register [P1] the lower value register
Scale Basic Function [P2} the scale basic function to execute when lower >= upper
The next program uses 2 events: F1 key to start things off, and a setpoint monitor. This
program also uses a TTL output (Relay 1). NOTE: use test circuit shown at beginning of this
section.
Application Description
Drums are placed on the scale. Tare the scale, and then fill drums with material. The fill amount
is fixed at 500 lb.
Outputs
Relay output 1 used to fill valve.
Inputs
F1 key starts operation
setpoint amount (500 lb)
Sequence of operation
Operator presses F1 key [Keyboard Event]
Tare the weight on the scale.
Turn on fill valve.
Monitor weight until Net >= setpoint amount [Setpoint Event]
Turn off fill valve.
From the Inputs section above we can fill in the Events section of the design template. The F1
key is used to start the fill process. Use it to activate User function 1.
The setpoint amount presents us with a new type of event, the Setpoint Monitor. Recall from
the previous section of this manual titled “Event Driven Programming” that the program
structure is event, action, event, action….
The first event is the F1 key. The action is to begin the fill process (tare the scale, turn on fill
valve, turn on setpoint monitor). When the setup is complete, the process must wait for the next
event (Net weight >= setpoint amount).