New BusWorks 966PB input modules interface up to six RTD or resistance signals directly to a Profibus-DP network. These independent input devices do not require expensive additions such as the bus-couplers and mounting racks needed by modular or block I/O systems.

Each inch-wide module contains a 16-bit A/D converter, a microcontroller for intelligent signal processing, and an SPC3 ASIC to communicate with the Profibus network. Priced at $500 for a four-input unit or $650 for six inputs, they are appropriate for applications that need to monitor a small quantity of RTD sensors per site.

Each unit accepts universal RTD/resistance inputs with user-selectable ranges for platinum, nickel, or copper RTD sensors and 0-500 ohm signals. A built-in RTD sensor break detection feature senses wiring failures and invokes upscale or downscale failsafe output. Three-way 1,500 Vac isolation between the input, network, and power circuits protects against surges and ground loops.

The 966PB uses standard 12-36 Vdc supplies instead of proprietary power packs. It automatically detects the network baud rate and supports high-speed communication rates of up to 12M baud. Network addresses are 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.