5.3 Digital Control Input Signals
Trillium Compact seismometers have two digital control input signals: UVW and CTRL. UVW
changes the output mode (which is XYZ by default) to UVW mode. By default, CTRL enables
the calibration function. You can reconfigure the CTRL control line to activate short period
mode (the default is long period mode) instead. The seismometer will respond to changes in
the state of the control signal within 5 s.
1. Long period mode is the normal mode for collecting seismic data. However, you
may want to use short period mode when bench-testing the Trillium Compact, such
as by tilting the instrument to see the response of the mass position outputs. When
in long period mode, the mass positions ramp very slowly and changes due to tilt
may take several minutes. In short period mode the mass positions respond within a
second, allowing you to watch the effects of tilting the instrument.
2. The UVW/TX input control signal is disabled when the seismometer is transmitting
serial communications because this pin is used as the RS-232 serial Tx output signal.
For more information on serial communication with a Trillium Compact, see
RS-232 Communications" on the previous page
and
Each input is optically isolated from the input voltage, the output signals, and the calibration
input signals. Therefore, signals applied to these pins must be referenced to DGND rather
than ±PWR or AGND.
All of the control input signals are active-high signals. See
"Connectors and Cables" on page 79
for details. All inputs can tolerate at least ±15 V except for UVW/TX which can tolerate voltages
from -7 V to +15 V. The CTRL and UVW control lines are shared with the serial RS-232 port (see
"Calibration Input Signal" below
). It is recommended that you use +12 V to activate these
control lines and high impedance for deactivation.
5.4 Calibration Input Signal
The Calibration Input Signal is provided to allow for relative calibration of the Trillium Compact
seismometer across frequency and over time.
Since the Trillium Compact is a symmetric triaxial seismometer, calibration is best performed
on the individual axes (UVW) rather than the horizontal and vertical outputs (XYZ). Individual
Chapter 5 - Input & Output Signals
16889R10 • 2020-11-12
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