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Model MD908 ‘IRIS’ Tilt Switch

The IRIS Tilt Switch and Controller is a powerful tilt controller device that combines a digital, dual-axis clinometer and advanced firmware features in one compact unit. This remarkable instrument enables you to measure and respond to rotational movements in any direction concerning the unchanging gravity vector. Units ship standard with a 24-inch hook-up cable. IRIS is an ideal choice for OEM applications, where it can be used to maintain platform levelness, avoid tip-over conditions, prevent out-of-range movement, and perform other control functions.




A Full-Featured Inclinometer

The IRIS Tilt Switch and Controller is a versatile biaxial clinometer that measures rotational movement in two orthogonal vertical planes. Serial ASCII data are output as either RS-232 or RS-422 (RS-485 full-duplex) signals for recording by an external terminal or computer. Important features are firmware-controlled and user-selectable. These include output data rates and formats, signal averaging, autozero (nulling), and internal data storage (logging). Several output data formats are provided, all of which include X tilt, Y tilt, Temperature, and Serial Number information.


A Powerful Control Device

The firmware on the standard IRIS board has 5 user-programmable thresholds. When a tilt measurement is taken, it is compared to each of these thresholds: +X tilt, -X tilt, +Y tilt, -Y tilt, and tilt in any direction. If the measurement exceeds one or more of the thresholds, the corresponding output pin(s) in the H3 connector, is set high (5V), as shown below. If the threshold is not exceeded, the output remains at 0 Volts. The reference angle for the threshold measurement is selected using the autozero command. Threshold checking may be turned off with a single firmware command when it is not needed.

The standard IRIS firmware also allows the user to set the hysteresis of the control thresholds. The hysteresis is used as follows: After an H3 output pin is set high, it is not set to low again until the tilt reading has reached a level that is below the threshold by an amount equal to the hysteresis (see diagram).

The IRIS includes 3 additional control output pins in the H3 connector, bringing the total to 8. These 3 additional pins are not active in the regular versions of the product but may be implemented for your application by custom programming by our software engineers. Each of the 8 control outputs is separately programmable. Another custom option is the “normally high” control output instead of the standard “normally low” output. With “normally high” controls the voltage level of the H3 pin is 5V until a threshold is reached, at which time it switches to 0V.

In standard IRIS models, the control pins in connector H3 are all set high for approximately 150 milliseconds on power-up, after which they reset to their “normally low” value of 0V until a tilt threshold is detected.

Additional information

Weight 1.1 oz
Dimensions 2.6 × 2.6 × 1 in

• 5 user-programmable thresholds
• TTL-compatible CMOS outputs (0-5VDC)
• RS-232 or RS-422 (RS-485 full-duplex) output
• Measures rotational movement in two orthogonal vertical planes
• Output data formats for X-tilt, Y-tilt, temperature, and serial number
• Sensitive to <0.002°
• User-programmable settings include: AUTO-zero (tare), sample averaging, and hysteresis control

Performance Specifications

Angular Range (°)±10±25±50
Resolution (°)0.0020.0040.01
Repeatability (°)
Non-linearity (%)111
Output Voltage (V)RS-232, RS-422 (RS-485 full duplex)
Output FormatNMEA XDR, Trimble TCM, BAE, Ashtec compatible, Simple (default: X, Y, Temperature, S/N)
Temperature OutputOn-board temperature sensor
Sample Rates10 samples/second to 1 sample/24 hours
Baud Rate9600 (default), 19200, 28800, 57600, 115200, 230400
Data FormatNMEA XDR, Trimble proprietary, Ashtech compatible, Simple (x, y, temperature, serial number)
ChannelsX-tilt, Y-tilt, Temperature, Serial No.
Tilt Switch Controls8 TTL-compatible CMOS control outputs (0-5 VDC); 20mA source Power per channel (not to exceed 100mA across all 8 channels)
Kz Coefficient (°/C, typical)10 arcsec
Ks Coefficient (%/C, typical)0.03
Time Constant (seconds)0.15
Natural Frequency (Hz)7
Input Voltage (Hz)7-28 VDC, 250mV ripple max
Input Current (Hz)27-30mA for RS-232 output
48-51mA for RS422/485 output
Current draw over the whole operating temperature range
If the H3 header outputs are used, this may draw up to an additional 20 to 100mA
ProtectionReverse polarity & surge protection
Power7-28 VDC, 250 mV ripple max, reverse polarity protected
Environmental-40 to +85°C operation and storage. 100% humidity, IP65
ConnectionsThree 60cm (2 ft) cables included: Signal (H1), Power (H2), Control Outputs (H3)
MaterialsGlass electrolytic sensor, fiberglass PCB

*Specifications subject to change without notice on account of continued development.


Outline Drawing
User Manual