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A-D converters: Sable UI2 |
Note for all A-D converters: Modern Macs lack built-in serial ports, so you'll need a USB to serial converter and driver software. The units made by Keyspan (now, TrippLite), specifically the USA-19HS, function reliably with LabHelper. Other brands have not worked well, or at all.
Sable Systems Universal Interface 'UI2' This is the default, preferred A-D converter for LabHelper and is a good compromise between speed, versatility, and cost. Although serial-based A-D converters are intrinsically slower than most internal A-D cards, the Sable UI2 is quite capable. UI2's have eight channels of high-resolution analog-to-digital conversion (± 5 or ± 5.12 volts depending on model), 4 channels of temperature conversion (thermistors) that can also be used to measure positive voltages or resistances, a counter, two analog output channels (0-5 volts), a serial input channel, and eight digital I/O lines that can be directly connected to digitally-controlled external devices such as gas flow multiplexers. Some users find the UI2's BNC connectors to be a bit of a pain, because many non-Sable instruments have other kinds of voltage output connectors. But since there are only two conductors involved, a little splicing and soldering are all that's necessary to make an appropriate hybrid cable.A standard 'straight-through' male-to-female DB9 cable should be used to connect the UI2 to the computer (more specifically, to the USB --> serial converter; see above). Since the communication speed is fairly high, do not use a cable longer than a couple of meters. |
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