Thin serial cable technology included in IEEE 1394 open standard slashes interface costs.
The IEEE 1394 standard defines a state-of-the-art interconnection scheme. ServoWire dramatically reduces the installed cost and hassles of system wiring. A traditional servo system has 20-25 connections per servo axis for proper system operation. ServoWire eliminates hundreds of electrical signal terminations with simple, plug-together cables.
The cable and connector design are part of the IEEE 1394 open standard … and are essential technology to delivering the high-speed serial bus communications. Highly engineered and reliable, the cables and connectors are patterned after those made by Nintendo for their Gameboy units.
IEEE 1394 cable design
Standard 1394 cables contain two power conductors, and two twisted pairs (TPA and TPB) for data signaling. Each signal pair is shielded and the entire cable is shielded. Cable power is specified to be from 8 to 40 VDC at up to 1.5 amps and is used to provide interface power for drives connected to the bus.
Molex shipped the first 1394 cables, connectors and headers for use in products. They played a key role to insure that the entire mechanical and electrical designs would be included in the IEEE 1394 standard to guarantee compliant second-source cables would be available.
ServoWire utilizes plug-n-play technology to bring ease-of-use to a new level.
IEEE 1394 implements a 'tree' topology, with repeater hardware in each interface rather than a ring (so there is no need for terminators or a hub). The tree structure, and the fact that 1394 uses automatic ID assignment, eliminates the need to set physical addresses before attaching a new servo drive to the network.
ServoWire uses 'plug-n-play' technology provided by IEEE 1394 to expedite setup and commissioning of devices on the ServoWire network. With a ServoWire system, the ORION controller searches for servo drives on the network at power-up. Servo drive IDs are displayed on the drives’ seven-segment LED, and incorrect or unassigned IDs flash are resolved by pressing a button on the drive to select the correct ID. Drive parameters are downloaded as defined by the software, and can match a single servo drive to a wide variety of motors.
This approach simplifies replacement of servo drives in the field. New drives are installed 'as received' since off-line, computer-based setup is not required to properly configure the new unit. The installer simply selects the appropriate ID, and the servo drive 'self-configures'--- reducing spare parts and setup complexity.
The fact that 1394 cables provide power for the ServoWire interface in the drives allows the network to operate, even without power to some of the drives in the network.