OIAC2 2-Axis +/-30deg Tilt Sensor
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General Description Optoi OIAC2 is an absolute inclinometer, based on MEMS (micro electro mechanical systems) technology 3-Axis accelerometer. The device is able to sense tilt angles over ±30 degrees range in the pitch and roll axis. OIAC2 belongs to a new category of inclinometers, that are compact, low cost, rugged, fast and very flexible. The accuracy in both angles is ±0.5 deg in the whole angle and temperature ranges. OIAC2 detects mathematically the tilt angles, based on all sensed accelerations (gravity) applied to the inclinometer along the X and Y axis. The signals are then filtered using an analog second order low-pass filter with cut-off frequency of 20Hz (fixed filter) and a user programmable digital filter (variable filter). The sum of these filters produces a formidable noise rejection (to vibrations for example) on the measured angles. The digital filter is a moving average filter, which is programmable from 1 to 1000 samples. The noise is reduced increasing the number of samples on which the signal is averaged and also the measured angle is less sensible to the vibration. However a larger number of samples coincides with a longer response time. Applications Construction Equipments Solar Farms Warehouse Automation Agricultural Machines Building automation Mining Equipments Car and Truck Overturn Alarm Systems ■ Accuracy of ±0.5 deg in ± 30°range, both axis, whole temperature range ■ Very fast sampling rate (up to 550 S/s) ■ CANopen bus interface ( protocol conform to CANopen Draft Standard 301 v4.02 ) ■ ±30 deg capability in pitch and roll axis ■ Wide (9-36V) power supply range ■ MEMS Technology ■ Anti-Vibration flexible filter ■ Small dimension 30(H)x70(L)x88(W) mm ■ Reduced temperature drift ■ Field Programmable ■ Factory Calibrated ■ Customization available on request Name Function Socket (female) 4 Data AH CAN_H bus line (dominant high) 5 Data BL CAN_L bus line (dominant low)

Detailed Description______________________________________________ Axis Orientation Pitch And Roll angles concept CAN bus line wiring scheme OIAC2 doesn’t have any internal bus line terminator resistor, so the user must take care of this aspect, connecting the 120ohm terminator at the beginning and at the end of the bus.

Node ID and Supported Baud Rate Any change applied at the Node ID and Baud Rate will have effect only after the node reset. The reset can be an hardware reset or also a software reset, issued with “Reset application ” or “Reset communication ” NMT frame. These parameters are infact saved immediately in the non volatile memory of the node, and only after reset all the COB ID’s are recalculated, according to the pre-defined connection set. It’s possible to restore the default values of Node ID and Baud Rate, writing the “load” string in the “Restore default parameters ” object in the object...

Network management objects During the boot-up procedure the node sends two different boot-up messages; after the node initialization is completed the device enters in the pre-operational state.

Writing Data in the Object Dictionary To write a parameter in the object dictionary the user must send an SDO Download Request Frame to the device, specifying the address and the eventual sub-index of the desiderate object. The length of the value sent to the OIAC2 can be 1byte, 2byte, 3byte or 4byte long. The segmented transfer for data length above 4 bytes is not supported by this device. The OIAC2 will answer to the SDO Download Request Frame with another SDO frame, which will contain the value corresponding to the specified address (address and eventual sub-index if needed). SDO...

OIAC2 in operational mode The OIAC2 inclination sensor is designed to operate in two different operational modes: • Two axis ±30 degree inclinometer (main mode) • One axis full 360 degree inclinometer To set the operational mode it is necessary writing the object in the dictionary at index 0x320C sub-index 0x00. By default the two axis operational mode is selected (object value 0x01). Depending on the selected operational mode for OIAC2, different PDO frames are enabled/disabled:

OIAC2 TX-PDO transmission type While CANopen specifies different transmission types, the OIAC2 implements only transmission type 0xFE ( 254 ), that corresponds to the asynchronous event-driven transmission type. This means that the PDO frames are transmitted when the value change respect to the last transmitted value. It’s possible to set also an event timer to force PDO temporized transmission, even if the value does not change. This event timer can be configured with SDO Download Request Frame, writing the corresponding PDO communication parameters object in the dictionary. These address...

OIAC2 Where frequency is expressed in radians per sample, the sampling rate is 550. Figure 2 – step response in time domain with 550 samples filter The damping time (or response time) can be calculated dividing the number of samples averaged per reported position by 1.82 milliseconds (sampling time). Td where Td is the damping time and Ts is the sampling time (fixed at 1.82ms) Ts Example: if the user wants to have a damping time of 1second (see figure above), the number of samples which must be set into the filter is: 1000/1.82 = 550 samples.

Pitch detection Pitch and roll detection Alarm thresholds