Drives and Controls Magazine

SSI and RS232 devices hook onto DeviceNet

01 November, 2002

SSI and RS232 devices hook onto DeviceNet

Rockwell has developed a pair of modules that allow SSI absolute positioning modules and equipment with RS232 ASCII interfaces to operate as nodes on DeviceNet networks.

The SSI (synchronous serial interface) provides high-speed transmission of complex absolute encoder positioning information for motion control applications. It is used by devices such as absolute rotary encoders, and linear and optical transducers.

Rockwell`s 1734-SSI module converts an SSI datastream into position data for transmission over DeviceNet. Data sizes, communication rates and delay times can be set by the user, helping to cut design costs and spare parts inventories. Rockwell estimates that there are more than 60 SSI-enabled devices from more than a dozen vendors that will work with the module.

The companion 1734-232ASC module is a single-channel RS232 interface for intelligent devices using RS232 ASCII communications, offering transmission rates up to 38.4kbaud. It can be used in retrofit applications when a company installs a fieldbus to integrate its factory-floor devices. Instead of replacing existing RS232 devices, they can be linked to a new DeviceNet network using the modules.