Relay module fronts up wireless serial modem

An Acces I/O Products product story

Edited by the Electronicstalk editorial team Feb 20, 2006

The latest addition to the range of wireless data acquisition products from Acces I/O Products is the Model WM-IIRO-8.

The latest addition to the range of wireless data acquisition products from Acces I/O Products is the Model WM-IIRO-8.

The unit features eight Form C (SPDT) electromechanical relays and eight optically isolated digital inputs with change-of-state interrupt generation.

The WM-IIRO-8 is an intelligent 8bit parallel digital I/O unit that communicates with an Acces wireless serial modem (sold separately) via a 900MHz wireless connection.

Up to 255 devices can easily be used with one wireless serial modem which connects to a host computer's standard COM port using RS232 (or RS485) serial communications.

Both the WM-IIRO-8 and wireless serial modem are packaged in small, rugged, NEMA4 enclosures; perfect for remote installations in harsh atmospheric, industrial, or marine applications.

The unit offers a low-cost alternative to costly signal wire installations in applications such as agricultural and irrigation systems, building management and control, security, and factory automation.

A text-based command/response protocol permits communication with most computer systems.

The unit can operate at distances up to 11km line-of-sight (up to 32km with optional antenna).

The eight isolated inputs can be driven by either DC sources of 3-28V (or higher by special order) or AC sources at frequencies of 40Hz to 10kHz and are not polarity sensitive.

Input signals are rectified by photocoupler diodes.

External resistors connected in series with the photocouplers may be used to extend the input voltage range.

Each input circuit contains a low-pass switchable filter to accommodate AC inputs.

The electromechanical relay outputs may be programmed individually or as an 8bit byte.

These outputs may be latched or pulsed for a prescribed period of time.

The relays are de-energised at power-on.

A microcontroller gives the WM-IIRO-8 the capability and versatility expected from a modern, stand-alone, distributed control system.

A built-in watchdog timer resets the pod if the microcontroller hangs up.

Data collected by the unit can be stored in local RAM and accessed later through the computer's serial port.

The WM-IIRO-8 is supported for use with virtually any computer and includes a text-based Windows software package.

Text programming permits users to write applications in any high-level language that supports ASCII string functions.

This package contains a graphical setup program along with sample programs and source code in Visual Basic, Delphi, C++ Builder, and Visual C++.

A Windows-based application is included that allows for establishing communication, quick setup and testing of I/O.

The program displays all inputs and outputs simultaneously, and allows for one-click operation.

Full source code is provided, as well as a number of other samples in a variety of languages to demonstrate techniques for developing custom applications for logic functions etc.

The board can also be used as a stand-alone controller with the help of a firmware development kit.