HMR2300r

Honeywell's three-axis strapdown magnetometer detects the strength and direction of the earth's magnetic field and communicates the x, y, and z component directly via serial bus. The HMR2300r is compliant with applicable MIL-STD- 810E requirements for military and commercial flight systems (see Table 6). It was designed to be a replacement for bulky fluxvalve magnetic sensors commonly used in aviation systems.

The HMR2300r strapdown magnetometer provides an excellent replacement of conventional fluxvalve sensors, commonly used in aviation systems today. The HMR2300r offers higher reliability (MTBF >50,000 hours) that reduces maintenance and repair cost. Since the design is strapdown, as opposed to a gimballed fluxvalve, it has no moving parts to damage or wear out during severe flight conditions. Low cost, high sensitivity, fast response, small size, and reliability are advantages over mechanical or other magnetometer alternatives. With an extremely low magnetic field sensitivity and a user configurable command set, these sensors solve a variety of problems in custom applications.

A command set is provided (see Table 4) to configure the data sample rate, output format, averaging and zero offset. An on-board EEPROM stores any configuration changes for next time power-up. In addition, the user has 55 bytes of EEPROM locations available for data storage. Other commands perform utility functions like baud rate, device ID and serial number. Also included in the HMR2300r magnetometer is a digital filter with 50/60 Hz rejection to reduce ambient magnetic interference.

A unique switching technique is applied to the solid-state magnetic sensors HMR2300r to eliminate the effects of past magnetic history. This technique cancels out the bridge offset as well as any offset introduced by the electronics. The data is serially output at either 9,600 or 19,200 baud, using the RS- 422 or RS-485 standard. The RS-485 standard allows connection of up to 32 devices on a single wire pair up to 4,000 feet in length. An HMR2300r address can be stored in the on-board EEPROM to assign one of thirty-two unique ID  odes to allow direct line access. An internal microcontroller handles the magnetic sensing, digital filtering, and all output communications eliminating the need for external trims and adjustments. Standard RS-422 or RS-485 drivers provide compliant electrical signalling.