BRIC Operation

BRIC closure limits

As with other high-density units, for a BRIC the pipx40 driver imposes a limit on the maximum number of channel closures - see Closure Limits. Although pipx40_setDriverMode offers a means of disabling this limit, the extraordinarily high packing density in BRIC units makes observation of maximum closure limits particularly important. The consequences of turning on an excessive number of crosspoints can be appreciated from the fact that each activated crosspoint may consume around 10mA at 5V (50mW, or 1W per 20 crosspoints). The power consumption of a large BRIC with all crosspoints energised would be beyond the capacity of the system power supply and backplane connectors, never mind its cooling capabilities. For this reason BRIC units are fuse-protected against overcurrent. However, it cannot protect against local hot-spots within a BRIC if too large a block of physically adjacent crosspoints is energised. Although the fuse is self-resetting under moderate overload, a massive overload may cause it to rupture permanently.

BRIC daughtercard removal

In the event of a BRIC daughtercard being removed for servicing, operation of the entire unit is normally disabled. It is possible to allow continued operation in spite of this fault condition using the pipx40_MODE_IGNORE_TEST option bit in pipx40_setDriverMode. When this mode is set, the tests performed when the card is opened will still detect the fault and flag it in the card's pipx40_getCardStatus value (bit pipx40_STAT_HW_FAULT = set); however it will no longer be flagged as disabled (bit pipx40_STAT_DISABLED = clear), allowing continued operation.

Multifunction BRICs

Multifunction BRICs have independently controlled isolation switches. In operating these units it is advised that where hot-switching occurs programmers ensure that matrix crosspoint relays hot-switch, and isolation relays cold-switch. This avoids concentrating the contact wear caused by hot-switching in the isolation relays, which could lead to a reduction in their operational life. The preferred operating sequences for hot-switching are: