Jewell Instruments MD908 Specifications

Model MD908 “IRIS” Tilt Switch

Extra 24

-

in Cable Assembly, RS232 , H1

Extra 24

-

in Cable Assembly, RS422 , H1

24-in Tilt Switch Control Cable

The IRIS Tilt Switch and Controller powerful tilt
control device with advanced firmware features. The
on-board electrolytic tilt sensor is sensitive to

<0.002°. User programmable settings include AUTO-

zero (tare), sample averaging, hysteresis control, and
more. Units support RS232 and RS422 (RS485 full
duplex) output. The IRIS also supports a variety of
output protocols including Trimble TCM, NMEA XDR,
BAE, and Ashtech Compatible. Units ship standard
with 24-in. hook-up cable. Use the IRIS for industrial
pitch and roll measurement, platform leveling,
specialized OEM assemblies, scientific instrument
packages and more.

High-Gain Standard Wide-Angle
Angular Range
Resolution
Repeatability
Non-Linearity 1% 1% 1%
Output RS232, RS422 (RS485 full duplex)
Output Format NMEA XDR, Trimble TCM, Ashtec compatible, Simple (default: X, Y, Temp., S/N)
Baud Rate 9600 (default), 19200, 28800, 57600, 115200, 130400
Channels X-tilt, Y-tilt, Temperature, Serial No.
Tilt Switch Controls 8 TTL-compatible CMOS control outputs (0-5 VDC);

Kz Coefficient (deg/C)
Ks Coefficient (%/C)
Time Constant 0.15 sec
Natural Frequency 7 Hz
Power 7-28 VDC @ 30mA, 250 mV ripple max, reverse polarity protected
Environmental -40° to +85° C operating and storage; 90% humidity non-condensing
Dimensions 67 x 67 x 25 mm, 31g (1.1 oz)
Materials Glass electrolytic sensor, fiberglass PCB

Specifications subject to change without notice on account of continued product development

±10° ±25° ±50°

0.002° 0.004° 0.01°

0.01° 0.01° 0.02°

20mA source Power per channel (not to exceed 100mA across all 8 channels)

10 arcsec/°C (typical)

0.03%/°C

Ordering Code: Accessories:

P/N Description

84063-01

84088-01

84083-01

00254-02 Transformer, 100-240VAC to 12VDC

Header to DB9-sub Connector

Header to DB9-sub Connector

(Connects to H3 Terminal), Tinned Ends

Jewell Instruments LLC 850 Perimeter Road, Manchester, NH 03103

[e-mail] • www.jewellinstruments.com • Tel [phone]

L00258 Rev. A

Model MD908 “IRIS” Tilt Switch

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 RS232 or
RS422(RS485 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, are 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 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 “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.

Jewell Instruments LLC 850 Perimeter Road, Manchester, NH 03103

[e-mail] • www.jewellinstruments.com • Tel [phone]

L00258 Rev. A