Alpha 636 Isolated Digital and Analogue I/P Processor

Description

What is the Alpha 636 Isolated Digital and Analogue I/P Processor?
The Alpha 636 module provides six digital input channels for counting, frequency or status measurements. Counting and frequency measurements on these channels support input rates 15Khz.

The first four channels can also be configured in pairs as one or two quadrature phase decoder channels for rotary and linear and displacement sensors. Four independently isolated analogue channels are included, with input range options. Each of these analogue channels has it’s own ADC running continuously.

The technique used is continuous integration, which offers the best noise performance in real world conditions by using all the available signal instead of sampling the signal at discrete intervals.

The primary integration period is 3.3mS. Typically, three measurements are averaged to present 100 samples per second per channel. Other integration times can be programmed for each channel, enabling measurements to be made with high 50 or 60Hz mains interference rejection and fast update rates.

Each analogue channel is fully independently isolated from all digital inputs and other analogue channels using solid-state transformer isolation. This eliminates ground loop effects and provides protection to the equipment in the event of faults or incorrect wiring of input connections. It also makes an overload of on one channel much less likely to affect other channels.

Four additional lower speed op-to-isolated channels are provided for count, low frequency, period interval, rpm and digital status measurement. These channels support counting and frequency measurements to 1KHz, and period measurement to a resolution of 1mS. Multiple period measurements can provided a resolution down to 10uS.

Six isolated and fused relay outputs are provided as general purpose outputs. Complete measurement scans of all channels are typically completed at 100 scans per second or higher.

To maintain accurate measurement intervals and to allow a host computer some variability in communication times, the measurements are efficiently packed into a First In First Out (FIFO) measurement buffer with each 636 module.

The Alpha 636 standard firmware supports normal use of the I/O facilities returning measurements efficiently to a host computer using a RS485 communications port.

Up to 99 modules can be connected to a single RS485 network. The firmware can be easily customized for specific application requirements.

LOCAL SERIAL INTERFACE
As with other modules in the Alpha series, a local serial interface can be used to program and monitor operating locally independent of the communications on the RS485 network.

This can be very convenient during installation or sued later to diagnose application problems at the measurement site.

Alternatively, it could be used with a permanent local process display. Customized display output can be provided. All configuration settings are stored in secure non-volatile flash memory.