Owner's manual

78 Rockwell Automation Publication 1756-UM536A-EN-P - April 2012
Appendix C Alternate Wiring for Non-IEC Type 3 Sensors
Choose a Pull-up Resistor for
an Open Collector Sensor
To choose a pull-up resistor for an open collector sensor, use the module’s
nominal input current specifications in Table 8
and the transistor’s current rating
to calculate the voltage drop across the pull-up resistor when the transistor is Off
and On:
– Choose a pull-up resistor that provides a minimum of 10V at the
module terminals when the transistor is Off (input module is On).
– Choose a pull-up resistor that provides a maximum of 5V at the module
terminals when the transistor is On (input module is Off ).
Table 9
shows examples of two pullup resistor values with various power supply
voltages and their actual measured values.
Open Collector Wiring
without a Resistor
If the off-state current of your open collector device complies with the module's
off-state current specification of <1.5 mA max, the device may be wired as shown
below. The module's input impedance will function as the pull-up resistor.
Table 9 - Pull-up Resistor Examples for Open Collector Sensors (actual measured values)
R_Pullup
(Ohms)
V_Supply
(Volts)
V_Terminals
(Volts)
V_R_Pullup
(Volts)
I_R_Pullup
(mA)
P_R_Pullup
(Watts)
499 12 10.1 1.9 3.8 0.00722
499 24 21.6 2.4 4.8 0.01152
499 30 27.5 2.5 5 0.0125
1000 12 9.2
(1)
(1) A 1000 ohm pull-up resistor is not recommended for 12V applications because it does not provide a minimum of 10V at the
terminals.
2.8 2.8 0.00784
1000 24 19.3 4.7 4.7 0.02209
1000 30 25.1 4.9 4.9 0.02401
1
3
5
7
019
2111
4131
6151
8171
0291
2212
4232
6252
8272
0392
2313
4333
6353
GND-0
GND-1
GND-2
GND-3
CTR-GND-0
GND-4
GND-5
GND-6
GND-7
Not Used
CTR GND-1
CTR GND-2
CTR GND-3
CTR GND-4
5
6
7
7
IN-0
IN-1
IN-2
IN-3
CTR-0
IN-4
IN-5
IN-6
IN-7
Not Used
Not Used
CTR GND-
CTR GND-
CTR GND-
CTR GND-
CTR-1
CTR-2
CTR-3
CTR-4
CTR-5
CTR-6
CTR-7
2
4
6
8
1756-LSC8XIB8I
12…24V DC
+
-