Pulsafeeder Pulsar DLC - Manual (Page 21)

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5.6.1 Current Output
Current Output is calibrated to source current in the 0 to 20mA range (e.g., 4-20mA). The output can
be calibrated for reverse acting and split ranging and control. Refer to Section 7 – General Operation:
Calibration for further details.
Current Output is used to control slave devices (e.g., DLC's, ELMA's, PULSAMATICs, etc.) or to
fulfill closed loop system requirements. Attach the connection points labeled '1-CURRENT(+) and '2-
CURRENT(-)' on connector J5-OUTPUT (refer to Figure 6) to the external device. Use 0.32mm
2 –
0.52mm
2
(22-20 AWG) wire. Attach the Positive lead to position 1 and the Negative lead to position 2.
The analog output will drive against a maximum load of approximately 700 ohms. Thus, a single DLC
Analog Output could be used to drive two slave DLC's. They, in turn, could each drive two additional
slaves. The Analog Output is isolated from all other inputs, outputs and earth ground. Follow the
instructions in Section 7 – General Operation: Analog Output Signal Calibration.
5.6.2 Alarm Dry Contact Output
The Alarm output is a solid state transistor closure. It indicates the present state of the alarm relay
output. If the Alarm Relay is on, the Alarm Dry Contact will be closed. If the Alarm Relay is off, the
Alarm Dry Contact will be open. It is commonly used to indicate an alarm status to external control
equipment (i.e., PLC, PC or other Manual controllers). Refer to Figure 6.
VCC (+5VDC) and Ground are provided on terminals 7 and 8 of connector J5. A 250 ohm resistor
from terminal '7-VCC' to terminal '3-ALARM(+)' will cause a +5VDC signal to appear between
terminals '4-ALARM(-)' and '8-DCGND' when the Alarm Relay is on. This technique is only
recommended if the input on the external device is isolated from all other inputs, outputs and
grounds.
An opto-coupler is used to achieve total isolation of this output. As such, the external control
equipment must generate the supply on the positive output and detect the return of that signal from the
DLC. In a typical application, use 0.32mm
2 – 0.52mm 2 (22-20 AWG) wire to attach the terminal
labeled '3-ALARM(+)' – the collector terminal – to the external equipment's logic supply. Connect the
terminal labeled '4-ALARM(-)' – the emitter terminal – to the positive input of the equipment. The
negative input of the equipment should be connected to its isolated ground. A series resistance of 400
ohms is recommended – especially when sinking current (e.g., a photo-diode of an opto-isolator). The
Alarm output cannot be separately configured in the software, it follows the Alarm Relay output.