Stan Hoeppner wrote:
We bought DB25 plugs in bags of 100, and used spooled CAT5 as the noise rejection is many times that of CAT3, allowing greater distances across sprawling warehouses.
RS-232 uses single-ended signaling and requires shielded cable, twisted pair doesn't help either. The common-mode noise rejection of twisted pair only works if the signals connected to a balanced input receiver. Industrial RS-485 communication is one of these solutions, for example.