Connecting Devices to the Auxiliary Output Signals
Connecting Devices to the Auxiliary Output Signals
Integrate external devices with the auxiliary output signals from the scanner.
The auxiliary output signals can also interface with inductive load devices (such as a relay or a small motor).
The auxiliary output signals are sinking outputs based on an NPN-type transistor. They need to be connected to an external power source because they cannot provide voltage to drive a device independently. They are typically connected in a sinking configuration because they only have one dedicated pin (AUX_OUT0, AUX_OUT1, AUX_OUT2, respectively) and share their other pin (AUX_OUT_COMMON). So, typically, a sourcing device is connected to its dedicated pin, and the return path connects to the common pin. The exact connection between the output signal, the connected device, and the power source depends on the type of device to which you connect.
Sourcing Devices to Sinking Auxiliary Output Signals
You can also connect a single auxiliary output signal in a sourcing configuration, such that the common pin is connected to a sinking device, and the dedicated pin is connected to the power supply. However, the other two auxiliary output signals are unavailable in this configuration. The exact connection between the output signal, the connected device, and the power source depends entirely on the type of device to which you connect.
Soucing Auxiliary Output Signal to a Sinking Device
When an auxiliary output signal is on, the circuit between its AUX_OUT pin and AUX_OUT_COMMON pin is closed, allowing current to flow from the AUX_OUT pin to the AUX_OUT_COMMON pin if the AUX_OUT pin is attached to a power source or a sourcing device. When an auxiliary output signal is off, the circuit between the AUX_OUT and AUX_OUT_COMMON pins of the signal is open, and no current flows through.
The power source must be provided externally.
When the auxiliary output signal is attached to a device, observe the following:
Observed Voltage
Connection
Observed At
Observed Voltage
Signal on (closed so current can flow from AUX_OUT to AUX_OUT_COMMON pin)
Signal off (open so current cannot flow from AUX_OUT pin to AUX_OUT_COMMON pin)
The sourcing device is attached to the AUX_OUT pin, and the return path is attached to the AUX_OUT_COMMON pin
AUX_OUT pin
Low
Floating (the sourcing device imposes voltage level)
AUX_OUT_COMMON pin
Low
Low
The power supply is attached to the AUX_OUT pin, and the sinking device is attached to the AUX_OUT_COMMON pin.
AUX_OUT pin
High
High
AUX_OUT_COMMON pin
High
Floating (the sinking device imposes voltage level)
Auxiliary output signals only present one predictable voltage level for a given configuration: a low voltage level in a sinking configuration or a high voltage level in a sourcing configuration. Their other output state is, by default, floating. So, if you need to connect to a digital device that requires two predictable voltage levels to operate, pull-up or pull-down circuitry must be added.
External Pull-up Circuitry
Implement a resistance value of 3 KOhms to protect the scanner. Auxiliary output signals can sink up to 50 mA; use the documentation of your input to calculate the required resistance for your external pull-up/pull-down resistor (if necessary).
In the previous example, the pull-up circuitry causes an inversion if the device's input is connected to the AUX_OUT pin. When the auxiliary output signal is on, the circuit between its AUX_OUT and AUX_OUT_COMMON pins is closed, and current flows from the power source to the AUX_OUT_COMMON pin. As a result, the observed voltage at the AUX_OUT pin is low. When the auxiliary output signal is off, the circuit between its AUX_OUT and AUX_OUT_COMMON pins is open, and current flows from the power source to the device's input. In this state, the pull-up's resistor value limits the current.
The auxiliary output signals are compatible with voltages up to 24 V. However, by default, they offer low resistance. Current flows directly through them when they are on (their circuit is closed). Ensure that the circuit created between the power source, the output signal, the connected device, and the return path does not cause more than 50 mA to flow through the signal.
As a precaution, the auxiliary output signals are individually fuse-protected up to 50 mA. The device uses resettable fuses. The fuses protect the scanner if you accidentally connect the corresponding auxiliary output signal to a device that sources/sinks more current than the scanner can safely transmit. If more than 50 mA of current goes through your scanner, the fuse eventually trips. After disconnecting your scanner, the fuse resets after it sufficiently cools.
The following diagram depicts the scanner's on-board fuse.
