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Overview
The LLAC4 is a small peripheral that you can use to increase the number of low-level ac signals that your data logger can monitor. The LLAC4 is often used to measure up to four anemometers, and it is especially useful for wind profiling applications.
Benefits and Features
- Ideal for applications that require high numbers of pulse channels, but fewer control ports, such as in wind prospecting
Detailed Description
The LLAC4 enables four data logger control ports to emulate pulse-counting channels by converting the low-level ac signals to logic levels read by the control ports. To use the LLAC4, the data logger control ports must accept high frequency pulses. The LLAC4 typically measures anemometers but can measure other sensors that output pulse counting signals.
Minimum AC Input Voltage versus Output Square Wave Frequency
| Input Sine Wave (mV RMS) |
Output Range (Hz) |
| 20 | 1.0 to 20 |
| 200 | 0.5 to 200 |
| 2000 | 0.3 to 10,000 |
| 5000 | 0.3 to 20,000 |
Specifications
| Function | Increases the number of low-level ac signals that a data logger can monitor. |
| Number of Channels | 4 |
| Power | 0.1 mA (@ 12 Vdc) |
| Input Hysteresis | 16 mV (@ 1 Hz) |
| AC Coupling Removal of DC Offset | ≤ ±0.5 V |
| Maximum AC Input Voltage | ±20 V |
| Cable Length | 0.6 m (2 ft) |
| Dimensions |
|
| Weight | 92 g (3.2 oz) |
Compatibility
Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.
Enclosure Considerations
A desiccated, non-condensing environment is required. The MD485 includes built-in keyhole flanges for mounting to the backplate of a Campbell Scientific enclosure.
Combining with Other Devices
The MD485 can be combined with our AVW200-series Vibrating-Wire Interfaces, CC640 Digital Camera, Ethernet links, phone modems (including cellular), and spread spectrum radios. Field site equipment should be housed in an environmental enclosure. Information about configuring the other devices is provided in the user manuals.
Power Considerations
AC power is typically used at the computer site; a pn 15966 wall charger is required. At the field site, the MD485 is powered by the data logger through its CS I/O port. If the MD485 is connected to the data logger’s RS-232 port instead of the CS I/O port, or if the data logger was purchased before 12/97, a pn 14291 Field Power Cable is required. Phone-to-MD485 and spread spectrum radio-to-MD485 networks also require a power supply with a null modem port. An A100 adapter used with a PS150 or PS200 power supply provides this capability. The PS150 or PS200 is recharged via a wall charger or a solar panel.
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