Acromag--New Profibus analog output modules control up to six drives, valves, or displays based on network commands

  • April 08, 2003
  • Acromag
  • News
The latest I/O modules for Acromag’s BusWorks® 900PB Series convert instructions from Profibus network controllers to DC voltage or current signals for driving analog control devices.Wixom, MI: Acromag’s new BusWorks® 972PB and 973PB Analog Output Modules deliver data from a Profibus-DP network as voltage or current signals to as many as six measurement or control devices. Typical applications involve controlling valves, drives, motors, and variable level devices or providing analog signals for displays, recorders, and other non-networked process instruments and control systems. These independent output devices do not require expensive additions, such as bus-couplers and mounting racks like modular or block I/O systems, to deliver a more compact and cost-effective solution. Each inch-wide module contains a 12-bit D/A converter, a microcontroller for intelligent signal processing, and an SPC3 ASIC to communicate with the Profibus network. Priced at only $500 for a four-output unit or $650 for six outputs, they are very economical for applications that only need to control a few devices per site. Power requirements are very flexible. The 970PB modules operate off standard 12-36V DC supplies instead of proprietary power sources.The 972PB models provide DC current output with user selectable ranges of 0 to 1mA, 0 to 20mA, and 4 to 20mA. On the 973PB models, DC voltage output signals are selectable in 0 to 1V, 0 to 5V, or 0 to 10V ranges. Both units employ a 12-bit D/A converter to deliver highly accurate output signals. Three failsafe options let the user choose how outputs respond if network communication is interrupted. Failsafe outputs can be forced to the 0% output level, remain at the last known value, or set to any desired value in the range. To prevent damage from surges and ground loop errors, units have three-way 1500V AC isolation separating the output, network and power circuits.The isolated ProfiBus-DP network interface is highly immune to noise and operates dependably over long distances. 970PB units automatically detect the network baud rate and support high-speed communication rates of up to 12M baud. Network addresses are easily set via switches on the modules. A built-in watchdog timer monitors for network communication problems while self-diagnostic capabilities simplify maintenance and troubleshooting. A failsafe mode can be set to ensure outputs are sent to a safe state if a failure occurs.Many other features ensure dependable operation. All of Acromag’s 900PB series modules employ the industry-standard Siemens SPC3 intelligent ASIC to handle ProfiBus protocol and communicate with the network. An internal microcontroller has integrated non-volatile memory for reliable storage of configuration parameters and can be reprogrammed repeatedly. And to visually confirm proper operation, LEDs indicate power, network activity, and individual channel status. The units are pending certification by the ProfiBus PNO, as well as CE approvals and UL/cUL listings. Acromag, a multimillion dollar international corporation, has been developing and manufacturing measurement and control products for more than 45 years. They offer a complete line of industrial I/O products including process instruments, signal conditioning equipment, data acquisition boards, distributed I/O systems, and communication devices.For more information about Acromag products, call the Inside Sales Department or Marketing Communications at (248) 624-1541, (800) 881-0268, FAX (248) 624-9234, or write Acromag, Inc. at P.O. Box 437, Wixom, MI 48393-7037 USA. Information is also available on the Acromag web site at

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