ECT 464

1
ECT 464

• Lecture 4a
• Input/Output Modules

2
Most men forget God all day and ask Him to
remember them at night.

• Evening, morning and noon        I cry out in
  distress,        and he hears my voice.
• Psalm 5517

3
Typical Digital Inputs

• User Input
• Limit
• Proximity
• Temperature
• Flow
• Level
• Pressure

4
Typical Digital Outputs

• Lights/LEDs
• Solenoid Coils
• Alarm/Bell/Whistle
• Motor
• Relay

5
Input Modules

• AC
• Opto Triac Input
• DC
• Opto LED either sinking or sourcing
• Sinking- Current flows in input and out common
• Sourcing- Current flows in common and out input
  connection.

6
Proximity Switches

• Either Sinking (NPN) or Sourcing (PNP)
• Must be paired up with opposite input module
  logic.
• Sinking (NPN) current flows in the collector
  from the input module and flows out the emitter
  to ground. The input is a low signal felt on the
  base of the transistor.
• Sourcing (PNP) current flows in the emitter and
  flows out the collector to the input module. The
  input is a low signal felt on the base of the
  transistor.

7
Output Modules

• AC
• Opto Triac Output
• DC
• Opto-transistor either sinking or sourcing
• Sinking- Current flows in output and out common
• Sourcing- Current flows in common and out output
  connection.

8
Next Class

• Special Functions
• I/O scans and memory layout