ADInstruments PowerLab Owner's Manual page 12

For the /20, /25 and /26 series PowerLabs:
The negative (–) output is the complement of the positive (+) output, so the stimuli from
the two outputs are mirror images. If one output gives a positive voltage, the other
gives a negative one, and the two together give a diff erential voltage. One Stimulator
front-end such as a Stimulus Isolator or Stimulator HC can be connected to the positive
output of these PowerLabs.
Note: If you connect the Stimulator HC to a PowerLab that has an in-built Isolated
Stimulator, such as a PowerLab 26T, only the external, connected stimulator is used.
For /SP, /ST, /30 and /35 series PowerLabs:
Output 1 and Output 2 can function independently. However, only one Stimulator
front-end such as a Stimulus Isolator or Stimulator HC can be connected to the positive
output (Output 1) of these PowerLabs. With a Stimulator front-end connected, the
second output (Output 2) can function independently, and a second tab appears in the
Stimulator dialog in LabChart 7 for Windows. Therefore Output 2 remains available for
other uses, such as creating analog waveforms and triggering other systems.
Maximum Number of Front-Ends
2
The I C bus can control a maximum of sixteen front-ends. Therefore, if you are using a
PowerLab 16/30, which has sixteen input channels, you can record from sixteen single
channel front-ends.
Using ADInstruments Programs
Front-ends are designed for use with PowerLabs and ADInstruments programs such as
LabChart, LabTutor, LabStation and Lt. The functions of the front-end are combined
with those of the PowerLab, and are presented as a single set of soft ware controls in the
ADInstruments program. Depending on the front-end(s) connected, front-end-specific
dialogs replace the Input Amplifier dialogs or the Stimulator dialog.
The LabChart Help detail the Input Amplifier and Stimulator dialogs, and explain
relevant terms and concepts, but they do not cover front-end-specific features. These
features are described in detail in the following chapters for each front-end.
Front-end Drivers
A device driver is a piece of soft ware that allows the computer's operating system and
other soft ware to interact with a hardware device. ADInstruments applications like
LabChart communicate with a front-end via an appropriate front-end driver. These
drivers are automatically set up on the computer when ADInstruments applications are
installed, and their operation is usually invisible to the user.
However, under certain circumstances you may receive an error message during
the startup of LabChart indicating that there is a problem with the front-end driver.
Subsequently, the front-end will not function. This is invariably caused by the absence or
incompatibility of a driver required for communication with the front-end due to an old
version of the soft ware being run. The problem can be remedied simply by reinstalling
Owner's Guide
12