I want to connect a group of bus signals D[15:0] to GROUND in a schematic. The "GND" symbol is available in general list, but it is for a single wire only, not for a bus. When the GND symbol is connected to a bus, the schematic DRC error reports a "bus width mismatch." How do I connect a bus to GROUND (or VCC)?
A bus can have all signals connected to GROUND with the use of an iterative instance. The following example shows how to connect a 16-bit bus to GROUND.
1. Connect a GND symbol to bus signal D[15:0].
2. Name the GND symbol as an iterative instance (for example, instname = gnd_ins(15:0)). This step actually generates 16 instances of the GND symbol.
Alternatively, in ISE 9.1i and later, use the Constant symbol and set all values to 0.
See (Xilinx Answer 16526): "Schematic - How do I use constants in a schematic design?"