Input Wiring; Cable Shields; Sinking Sensors Require A Pull Up Resistor - Advanced Micro Controls Inc. SMD17E2 User Manual

SMD17E2 User Manual

1.6 Input Wiring

Inputs 1 and 2 are single ended inputs that share the DC Common return pin. They accept 3.5 to 27 Vdc with-
out the need for an external current limiting resistor. Figure T1.5 below shows how to wire discrete DC sourc-
ing and sinking sensors to inputs 1 and 2 of the SMD17E2. Colors in parentheses are the appropriate wire
color of the CNPL-5M cable.
PNP
Sourcing
Sensor
NPN
Sinking
Sensor

1.6.1 Cable Shields

Because they are low power signals, cabling from the sensor to the
SMD17E2 should be done using a twisted pair cable with an overall
shield. The shield should be grounded at the end when the signal is gen-
erated, which is the sensor end. If this is not practical, the shield should
be grounded to the same ground bus as the SMD17E2.

1.6.2 Sinking Sensors Require a Pull Up Resistor

Sinking output sensors require an external pull up resistor because
inputs 1 and 2 of the SMD17E2 units also sink current. Table T1.1
below shows the values of pull up resistors that will allow the unit's
input to activate along with the current that the sensor must be able to
sink when it is active.
Input
Voltage
5 Vdc
12 Vdc
24 Vdc
The logical states of the sensor and SMD17E2 input will be reversed. The SMD17E2 input is off when the
sensor is active. You can set the logic state of the input when you configure the unit.
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+
(WHT or BLK)
Out
–
See 1.7.1
+
(WHT or BLK)
Out
–
See 1.7.1
Pull Up Sensor Current
Resistor When Active
300 ohm
1.4 kilohm
3.8 kilohm
Table T1.1 TIA/EIA Color Codes
I
NSTALLING THE
Input1 or Input2
DC Common
(BLU)
See 1.7.2
R
PULLUP
Input1 or Input2
DC Common
(BLU)
Figure T1.5 Input Wiring
16.7 mA
8.6 mA
6.3 mA
SMD17E2
+
5 to
24 Vdc
+
5 to
24 Vdc
Input 1
Optocoupler
Input 2
Optocoupler
DC Common
Figure T1.6 Input Schematic
Input
Input
91