iRIS 350FX Reference Manual V1.50
11
HyQuest Solutions (NZ) Ltd
- PO Box 9466, Hamilton, New Zealand Tel: +64 7 857-0810 Email: [email protected]
Internal/External 12V Battery Supply
There are two terminals provided on the I/O connector desi12V and GND. These can be used to
power the unit from an external 12V battery or regulated dc supply. The internal battery is effectively
connected directly to these terminals. See Section
above for warnings on connecting external power
supplies to them.
External (Charger) Power Supply
Although the iRIS can operate solely from the internal battery for a few days if set to full power save mode,
you will typically need to connect an external supply to the unit so that the internal battery remains in a
charged state. You can connect any external dc power source ranging from 15 – 30Vdc, including a solar
panel, without requiring an additional solar regulator.
The battery charging circuitry utilises a switch mode regulator for maximum efficiency. The external power
supply is protected against over-voltage by ultra-fast acting protection devices and a self-resetting
semiconductor fuse.
It can also be used to charge an external battery connected to the GND and 12V+ terminals. In the event
that the external battery draws excessive current, the charger will enter a current limit mode (900mA) until
such time as the battery has been recharged sufficiently to deliver the full supply voltage. The charging
profile used by the charger depends on the selected mode. See the Power Management description in
Section
The battery charger operates in a simple dual mode “float” / “charge” pattern. To do this it regularly
switches between two voltage levels to optimise the battery charge. The actual profile is determined
by the Power Source setting.
When the Power Source is set to “DC”, the battery voltage will rise and fall every two hours giving a
“sawtooth” type voltage plot when the data is logged. This is normal.
Analogue I/O
Analogue Inputs
The four analogue inputs are uni-polar 0-5Vdc with 16-bit resolution. Each input presents a load impedance
of 97K
to the input signal.
Scaling factors should be chosen to convert from a raw value of 0.0000 – 5.0000, which reflects the input
signal range of 0-5V. When current sources such as 0-20mA or 4-20mA are connected, an internal sink
resistor (100
) is enabled by an internal user-settable link (J1-J4). In this mode the measured voltage range
is 0-2V for a 0-20mA input and the scaling factor should take this into account.
As the analogue inputs have an input impedance of 97K
, the actual sink resistor impedance will
be slightly lower than the value fitted. When, for example, the current mode link is fitted, a sink
resistor of 100 ohms is installed. The actual impedance will theoretically be 99.71
; therefore the voltage
measured by the iRIS will also be slightly lower than expected. See Section
recommended scaling method for optimising the calibration.
Summary of Contents for iRIS 350FX
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