Bullet Sensors & Transducers e-Digest, Vol. 57, Issue 7, July 2005: Product News

    (ISSN 1726- 5479)


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Ethernet I/O Modules Now Have the Ability to Speak Directly to Each Other Without a PLC, PC or any Other Controller


Wixom, MI. Acromag has enhanced their BusWorks 900EN Series Ethernet I/O Modules with a new capability allowing input modules to send measured signal data directly to output modules without a PLC, PC or other controller in between. This i2o (input-to-output) function is ideal for simple remote I/O applications where sensor signals at one location must be displayed, recorded or monitored across the plant or around the globe, but programming a controller is not desirable. Analog input modules measure current, voltage, or temperature signals at Point A and transmit the data to analog output modules that provide proportional 4-20mA or 0-10V DC output at Point B. Discrete input and output modules control local devices based on the level status of a remote device. Wiring costs are minimal because input and output modules can communicate between IP addresses across existing Ethernet network infrastructure, CAT5 cable, fiber optic lines, or via wireless radios. No software is required because the setup uses a standard Internet browser to configure an embedded web page.


Each remote I/O module has its own Ethernet Modbus TPC/IP port making it easy to connect the modules to each other with up to 100 meters of CAT5 cable. For longer distances or to reduce wiring, the I/O modules connect to a switch or radio modem to tap into copper, fiber, or wireless networks. Using a standard web browser, a simple configuration menu maps each input channel to an IP address and register for the output module. This process eliminates the need for a controller to poll the input module and transmit the data to the output module. Updates are user-defined for time-based or change-of-state.


Discrete I/O modules are ideal for on/off monitoring and control of motors, lights, heaters, valves and other industrial devices. A basic application would be to switch on a light in the control room if a cooling fan on the factory floor turns off. Twelve bi-directional channels allow discrete I/O modules to transmit and receive data on the same unit. The input channels are active-low with a 0-35V DC range and TTL-compatible. Output channels are open-drain DMOS mosfet switches with a 0-35V DC range for current sinking applications.

Analog input modules accept six differential 0-20mA, 10V DC, thermocouple, or RTD sensor signals and transmit the data across the network. Analog output modules receive the data and provide six 0 to 20mA or 0 to 10V DC control signals for displays, drives, recorders, or other instruments.


All units operate off standard 12-36V DC power supplies for greater flexibility. They also carry CE approvals and UL/cUL listing for Class I Division 2 installations. Three-way 1500V AC isolation separates the I/O, network and power circuits to prevent damage from surges and ground loops. An internal microcontroller processes the I/O signals and directs all operations. Built-in watchdog timers continuously monitor network communications while self-diagnostic routines simplify maintenance and troubleshooting. A failsafe mode can also be set to ensure outputs are sent to a safe state if a failure occurs. Integrated non-volatile memory provides reliable storage of the configuration parameters. And to visually confirm proper operation, LEDs indicate power, network activity, and individual channel status.

Ethernet I/O module





Robert Greenfield,

Acromag, Incorporate,

Tel: 248-624-1541

Fax: 248-624-9234

E-mail: rgreenfield@acromag.com



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