Dc Input Wiring Methods; Dc Output Wiring Methods - AutomationDirect C0-USER-M Manual

Chapter 3: Installation and Wiring

DC Input Wiring Methods

PLC DC Input
Input
Common
transistor output. When energized, it sinks current to ground from the DC input point. The
PLC input current is sourced from the common terminal connected to power supply (+).
DC NPN Sensor
(Sinking)
Sourcing Input Sensor (PNP Type) to PLC Sinking Input
In the following example, a field device has an open-emitter PNP transistor output. When
energized, it sources current to the PLC input point, which sinks the current to ground. Since
the field device loop is sourcing current, no additional power supply is required for the module.
DC PNP Sensor
(Sourcing)

DC Output Wiring Methods

CLICK PLCs and I/O modules with DC output circuits are wired as all current sinking only
or current sourcing only depending on which PLC or output module part number is used. DC
outputs typically operate in the range of +5-24 VDC.
PLC Sinking Output to Sourcing Load Device
Many applications require connecting a PLC output point to a DC input on a field device load.
This type of connection is made to carry a low-level DC signals.
In the following example, the PLC output point sinks current to ground (common) when
energized. The output is connected to a field device load with a sourcing input.
3–30
CLICK PLC Hardware User Manual, 5th Edition, Rev. F – C0-USER-M
CLICK PLCs and I/O modules with DC inputs can be wired as either
sinking or sourcing inputs. The dual diodes (shown in this diagram)
allow current to flow in either direction. Inputs grouped by a common
point must be either all sinking or all sourcing. DC inputs typically
operate in the range of +12-24 VDC.
Sinking Input Sensor (NPN Type) to PLC Sourcing Input
In the following example, a field device has an open-collector NPN
Field Device
Output
(sinking)
Ground
Field Device
=>
Output (sourcing)
Ground
PLC DC Output
Power
+DC Power
Output
(sinking)
Common
PLC DC Input
Input
(sourcing)
Supply
–
+
Common
PLC DC Input
Input
(sinking)
Common
Field Device
Input
(sourcing)
+
20-28 VDC
–
Ground
PLC Input
(Sourcing)
PLC Input
(Sinking)
=>