SMSEagle NXS-9700-3G, Руководство пользователя

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| SMSEagle NXS-9700 | User’s Manual
Port type Hardware Rev.3 Hardware Rev.2, Rev.1
DI 4 2
DO 4 2
The logical states of inputs and outputs of SMSEagle NXS-family of devices are represented by the following
states:
Logical level Hardware Rev.3 Hardware Rev. 2, Rev.1
LOW (0) +5 V 0 V
HIGH (1) 0 V +5 V
USING DIGITAL OUTPUTS
From digital output, without side effects, you can directly control external circuit with a voltage not exceeding
5V and a current of max. 450mA.
But the safest form of control external circuits is using an intermediary relay with a protection diode. Usage
example has been shown on the picture below.
Warning:
If you plan to use digital output with relay, it is recommended to connect a separate protection diode (a.k.a.
“snubber”) across the relay coil terminals as well. A diode snubber circuit can be added when ordering from some
relay manufacturers. This diode is installed in the direction that does not ordinarily allow current to conduct. When
current to the inductive load is rapidly interrupted, a large voltage spike is produced in the reverse direction as the
inductor attempts to keep current flowing in the circuit. Placing the snubber diode in parallel with the inductive load
for reversed-bias flow allows the current from the inductor to flow through the diode rather than through the
switching element, dissipating the energy stored in the inductive load from its series resistance and instead goes
through the much smaller resistance of the diode.