What is the maximum distance between a digital input device (remote switch) to a controller?
The maximum cable length between a digital input device and a controller is undetermined. The Airmaster products have been qualified as suitable for a level 3 environment, according to IEC 61000-4-4 with a cable length exceeding 3m.
A level 3 environment is known as a typical industrial environment. The area of industrial process equipment may be representative of this environment. The installation is characterized by the following attributes:
- No suppression of EFT/B in the power supply and control circuits which are switched only by relays (no contactors).
- Poor separation of the industrial circuits from other circuits associated with environments of higher severity levels.
- Dedicated cables for power supply, control, signal and communication lines.
- Poor separation between power supply, control, signal and communication cables.
- Availability of earthing system represented by conductive pipes, earth conductors in the cable trays (connected to the protective earth system) and by a ground mesh.
In general the longer the wire length of the Digital IO, the more conservative the wiring layout has to be. Physical separation of unshielded power supply and control cables from signal and communication cables, is strongly recommended to guarantee reliable operation of long wire lengths.