Product Description

The DBE 6501A converts between the standard single–ended parallel branch highway and a long–range differential highway. It may be used to extend a CAMAC branch up to 3 kilometres.

The Differential Branch Extender type DBE 6501A is a double width unit : two are joined to form a single two–way link. Each such link is ’transparent’ and can be fitted anywhere in the branch. The module nearer to the branch driver is known as the Transmitter; the other one is the Receiver. A switch on the module’s rear panel selects ’Transmit’ or ’Receive’.

The standard module has provision for an attenuation network in each differential line, so the user may adjust the sensitivity and common–mode voltage range of the link to suit the actual application. In addition, an integrating capacitor is fitted to the BTA, BTB and BTD lines to increase the skew between them and the data lines. This may be necessary where long cable runs are used, depending on the type of cable forming the link, when the variation in signal transmission time may approach the initial skew time.

Each module has two front panel sockets; one labelled CCSL is connected to a standard 66–pair parallel branch highway, and the other labelled DIFFERENTIAL is connected via the link to the same socket of another of these units. The DIFFERENTIAL socket has a different centre–boss orientation to prevent accidental misconnection of the single–ended highway to it, which might cause internal damage. They have the same pin–out.

As stated, the DBE6501A is ’transparent’, that is no test by the branch driver (or in Hytec System Crate terms, Branch Coupler) could detect whether a pair of DBEs were inserted into the branch highway or not. By the same token the unit has no Command Set, only taking power supplies from the Dataway. In order to prevent an operation on a long cable run (which would temporarily leave a significant charge to be dissipated) from causing errors on the next operation, should that operation be very quickly after the first, and to the crate controller where the Transmitter DBE was located, a switch is provided at the rear of the left–hand board, just beyond the side screen, which is used to select the addresses of ’remote; crates (beyond the DBE–DBE link). The Read–Write line receivers in the Transmitter are only Enabled when those crates are being addressed.

Specification

Signal standards.

Power Requirements

+6V at 3.5 amp max
–6V at 1.3 amp max
Total transient max
dissipation is 28.2W

CCSL Socket

Signals in EUR 4600/IEEE 596
Each line terminated in 100 ohms to +4V

Differential Socket

Signals are terminated in 124 ohms centre–tapped to 0V