Allen-Bradley MicroLogix 1200 User Manual page 46

3-12 Module Data, Status, and Channel Configuration
EXAMPLE
EXAMPLE
EXAMPLE
Publication 1762-UM003A-EN-P - February 2003
Engineering Units x1 to Scaled-for-PID
• input type = 200Ω Platinum RTD
• α = 0.00385°C
• range = -200 to +850°C
• desired channel temperature = 344°C (engineering units)
Scaled-for-PID Equivalent = 16383 x [(desired ch. temp. - S
Scaled-for-PID Equivalent = 16383 x [(344°C - (-200°C))/(850°C - (-200°C))] = 8488
Proportional Counts to Engineering Units x1
• input type = 1000Ω potentiometer
• range = 0 to 1000Ω
• channel data = 21567 (proportional counts)
Engineering Units Equivalent =
S + {(S - S
LOW HIGH LOW
Engineering Units Equivalent =
0 + {(1000 - 0) x [(21567 + 32768)/65536]} = 829Ω
Engineering Units x1 to Proportional Counts
• input type = 3000Ω potentiometer
• range = 0 to 3000Ω
• desired channel resistance = 1809Ω (engineering units x 1)
Prop. Counts Equivalent =
{65536 x [(ch. resistance - S
Proportional Counts Equivalent =
{65536 x [(1809Ω - 0) / (3000 − 0) ] } − 32768 = 6750
S = -200°C
LOW
S = 0Ω S = 1000Ω
LOW HIGH
) x [(ch. data + 32768)/65536]}
S = 0Ω S = 3000Ω
LOW HIGH
)/(S - S )]} - 32768
LOW HIGH LOW
S = +850°C
HIGH
)/(S - S
LOW HIGH LOW
)]