4-20 Ma Current Input - KMC Controls FlexStat Application Manual

4–20 mA Current Input
To use a 4–20 mA current input:
1. Connect an external 250 ohm resistor from input to ground. (Do not
install the resistor inside the FlexStat's case since the heat generated
by the resistor may skew the temperature readings.) The resistor
converts the 4–20 mA current input to a 1–5 VDC voltage that can be
read by the thermostat's analog-to-digital converter.
4–20
(–)
mA DC
(+)
NOTE: Custom programming is required
Pushed Left Pushed Right
External 250 Ohm Resistor for 4–20 mA Current Inputs
1
10K
2
1
3
2
2. Set the corresponding pull-up switches to the 0–12 VDC position.
4
5
6
10K
5
7
6 8
Input Pull-Up Switches Set to 0–12 VDC
FlexStat (General)
Inputs
IN4
IN3
250 ohms
GND
IN2
IN4 =
Ω
0-12 V
3 3
4 4
IN2 =
Ω
0-12 V
7 7
8 8
3. Using BACstage or TotalControl, configure the input device type for a
4–20 mA source.
Analog Input Configuration (in BACstage)
6 Application Guide, Rev L