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Hytec Electronics Ltd. |
CAMAC Serial Highway Fibre Optic U-Port Adaptors Types UPA 0542 (Master) and UPA 0541 (Slave)
Product Description
The CAMAC Serial Highway document (EUR 6100) specifies a ’defined port’, or D–Port, which is the electrical and mechanical interface between components of the highway. The transmission standard employed (RS–422) allows only a few volts common mode difference between the connected components of the highway so that for correct operation in electrically noisy environments it is necessary to convert to other transmission standards whilst retaining the message protocol of the highway. Where the transmission standard has been changed the interface is termed an ’undefined–port’, or U–Port, and such techniques as transformer coupling and bi–phase modulation are common. The unit which converts between the D–Port and U–Port standards is conventionally known as a U–Port Adaptor, and such a device may also contain the other elements of the Serial Highway such as the Bypass and Loop Collapse mechanisms.
One particular transmission technique which is useful in very noisy electrical environments is using fibre–optics. A highway link formed of an optical fibre cable is, of its very nature, immune to electrical interference and differences in earth potential between the ends of the link. Fibre–optic components are currently capable of bit rates up to 50 Mbaud which means that the CAMAC Bit–serial Highway maximum rate of 5 Mbaud is easily serviced.
The models UPA 0541 and UPA 0542 are U–Port Adaptors for fibre–optic transmission contructed as 19 inch rack–mounting, mains–powered units which combine the aspects of fibre–optic converters having both a main and back–up highway for redundancy, Bypass and Loop Collapse mechanisms, and a battery back–up facility for ensuring continued operation in the case of supply failure to a section of the highway.
The UPA 0541 is a slave unit which connects one or two Serial Highway Crates or crate clusters to the optical fibre link and the UPA 0542 is a master unit having no battery back–up which is intended for connecting the fibre–optic links to the Serial Highway Driver. Both units may be used to create Bit–Serial Highway structures operating at up to the maximum rate of 5 Mbaud and a maximum optical fibre link distance of 1 km between units. The Master may be configured to send or receive on the Main or Back–up Loops; the Slave will reconfigure itself automatically to match the Master’s configuration.
The optical–fibre links are coupled by means of the popular Amphenol 905 (SMA) termination and operate at a wavelength of 820 nm.
| Hytec Electronics Ltd Post : 5 Cradock Road, Reading, Berkshire, RG2 0JT, England. Phone : +44 (0)118 9757770 Fax : +44 (0)118 9757566 |