ECT 464

1
ECT 464

• Lecture 6a
• Analog I/O

2

• Todays Quote
• A marriage may be made in heaven, but the
  maintenance must be done on earth.
• However, each one of you also must love his wife
  as he loves himself, and the wife must respect
  her husband.
• Ephesians 533

3
Analog Input Devices

• We dont use special instructions to input and
  output analog values.
• Ports treated as specialty I/O
• Analog values are 16 bit signed integers
  (SLC-500)
• Analog Inputs and Outputs vary by PLC type and
  card
• /- 10 V
• /- 5 V
• 0-5 V
• 0-10 V
• 4-20 mA
• 0-20 mA
• /- 20 mA
• 1-5 V
• Single vs. Differential

4
Analog Measurements

• Position
• Speed
• Acceleration
• Weight
• Flow
• Level
• Pressure
• Temperature
• Distance
• Light

5
Analog Outputs

• Speed
• Valve Position
• Analog Meter
• Chart Recorder

6
Analog Input Addressing

• I3.0 Analog Input 0
• I3.1 Analog Input 1
• I3.2 Analog Input 2
• I3.3 Analog Input 3
• 8 bit analog input
• Bit 15 is always 0

7
Analog Output Addressing

• I1.0 Analog Output 0
• I1.1 Analog Output 1
• 8 bit analog input
• Bit 15, and 0-6 is always 0
• MVM (Move with Mask) instruction is used with a
  mask of 7F80h to move data to the output words

8
Analog Control Loops

• Output (Input-Feedback)Gain

9
Analog Control Characteristics

• Steady State Error
• Gain only is adjustable
• Critical gain
• Damping response
• Oscillation frequency