Chapter 2 Flashcards
Remote rack
located away from the processor module, linked to local rack through communication module
Address
label or number that indicates where a certain piece of information is located in a PLCs memory
Two general methods to programming
- address based
- tag based (give names to each components)
Rack/slot based addressing scheme
- type: determines if input or output
- slot: physical location of I/O module
- word and slot: used to identify actual terminal connection
Tag based
- base tag: defines memory location where data is stored
- alias tag: used to create alternate name for tag
Combination I/O modules
have both input and output connections in same physical module
Standard vs high density I/O module
- standard: has 8 inputs/outputs
- high density: up to 64 inputs/outputs
Most common type of I/O interface module
- called discrete
- connects devices that require simple ON/OFF switching (example: push buttons or lights)
- classification covers bit oriented inputs and outputs (each bit represents complete information element in itself)
What is a discrete I/O module powered by
field supplied voltage source
Discrete inputs/outputs
- inputs: push buttons, selector switch, limit switch, proximity switch
- outputs:indicator lights, signaling column, relays, motor starter
Discrete input/output module circuits are composed of two basic sections
- power
- logic
sinking/sourcing
- sinking: sinking current if device receives current when on
- sourcing: sourcing current if device provides current when on
discrete devices
inputs/outputs that have only two states: on and off
analog devices
represent physical quantities that can have an infinite number of values
status indicators are good for what
troubleshooting
