To minimise backplane interference 3-terminal (or similar) filters should be fitted to all the used power rails. The choice of filter can be design specific and there are multiple choices in the Pickering common library.

In mother / daughter card modules all component designators should be unique to each card. For example a module of 200 relays split equally across two cards should consist of RL1-100 on the mothercard & RL101 – 200 on the daughter card; having identical designators on both cards should be avoided.

Ensure that any unused relay pins (N.O. or N.C.) are included in the “Switch Path” net class. This can be done by assigning incrementing net names to these pins i.e. “NC1”, “NC2” etc. where “NC” equates to “not connected” and then attaching the “Switch Path” net class as per the switch paths.

Standard Pickering design practice dictates that there should not be any tantalum capacitors used. The most common value of tantalum capacitor used on Pickering designs is 10uF, 25V or 35V, these devices can be replaced with a ceramic equivalent, part reference C/CP/141.

As part of the schematic design for the module a block diagram is to be produced that will aid in the understanding of the module for the software / documentation teams. This is traditionally on the first schematic page(s).

Mechanical fixing points (screws, handles etc.) should be connected to “FP_Ground” if possible.

A spare relay should be provided on each module, space & card function permitting. For example modules with SMT relays would not be provided with a spare relay as these parts should be replaced in the factory. For mother & daughter card products the spare relay (if applicable) should ideally be on the mothercard but can be on the daughter card if unavoidable. The legend “spare relay” should be added to the component side silkscreen and ideally visible when the module is assembled.