Test Two Flashcards
What does HMI stand for?
Human Machine Interface
What can the HMI take the place of?
Hard wire inputs and outputs
What input can be sent to the PLC from the HMI?
Analog
What does the HMI send and receive from the PLC?
Sends and receives information and/or analog inputs or outputs
What is the input to the PLC such as the measurement of the water level in the tank? How can it be viewed?
Analog. It can be viewed by the operator at the HMI
How many pages does the HMI have the ability to have?
Multiple
How does the HMI communicate?
Ethernet
What could using a system that can accept an operator interface allow for control of the system?
Multiple Locations
What can be viewed on the HMI screen?
Graphs, trends, alarms, and outputs, from the PLC
Where can the set point be monitored from? How can this help the operator?
The set point can be monitored from the HMI and this can help the operator tune the loop
What do panel view and the PLC run on?
Separate Programs and 24 volts
What is the objective when tuning a loop?
Maintain a set point
In reference to a control loop, is over shooting known to be good or bad? How about undershooting?
It is a bad thing while undershooting is okay
What is one way to tell a control loop is not properly tuned or consistently meeting set points?
If it is inconsistent or hunting
What is it known as when an actuator controlling a process continually goes on and off?
Oscillating
What kind of inputs are from the HMI screen to the PLC for the solenoid valves?
Discrete inputs
What can you change from the HMI when accessing the auto level control for valve position or pump speed?
The set point
What do you have to do in order to tune the level control loop?
You need to access the PID block inside of RS Logix 5000
What does it mean if a control loop is hunting?
It could mean that it is in search for a better tune
What do the letters P,I,D stand for?
Proportional Integrative derivative
What do the 120v solenoid valves require to be actuated?
Solid state relay
How are the two solenoid valves on the discharge line of the lab station actuated?
By a 24 VDC signal from the PLC
What can using an HMI or a system with Ethernet communication enable the operator to do?
It can allow them to operate and monitor the system from remote or multiple locations
True or false- If the HMI were not available at the lab station you could operate the valves with the green push buttons on the outside of the cabinet. The VFD however would have to be operated from the keypad of the for start command and speed reference
False
