Rockwell Automation 44887-PUB, 44887 Enwatch - Manual (Page 7)

Publication GMSI10-UM031C-EN-E - January 2009
Installing the Enwatch 3
• Analog-to-digital converter (ADC) - The ADC samples up to
51.2 kHz and has 16-bit resolution, providing a theoretical dynamic
range of 96 dB.
• Clock generator - The timer varies the sampling rate under
microprocessor control. Sampling can be synchronized to one of 4
external triggers (typically a once-per-rev TTL signal from a rotating
shaft). This system can also take a preprogrammed number of samples
per revolution. The external trigger acts as a tachometer to determine
shaft speed. Pre and post-trigger functions are available.
• Gain amplifier - The Enwatch unit automatically sets the input gain in
auto-range mode as each channel is selected by the multiplexer.
• Microprocessor subsystem - This comprises the microprocessor,
flash memory, and SRAM memory. The microprocessor controls the
Enwatch unit under instructions stored in the flash memory. The SRAM
memory acts as a temporary data storage area if buffering is required
before data is transferred over the network.
• Watchdog - The microprocessor subsystem incorporates a watchdog
facility that, if a power glitch or other external effect interrupts the
system, automatically resets without the need for user intervention.
• Ethernet controller/buffer memory/10Base-T - These functions
control data transfer over the Ethernet network. The system uses the
UDP/IP standard protocol and implements 10 Base-T as the physical
network layer.
• Power regulation - Input DC power is derived from an AC to DC
converter (not shown in Figure 1.1) and the Power Regulation function
provides the secondary DC voltages as required.
Mechanical
The Enwatch unit is comprised of a single circuit board housed in a sealed (IP
66) enclosure. Each system has its own self-contained power supply, and
terminals for the input, power, tachometer, and network cables.
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