Current loop

In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time.

Given its analog nature, current loops are easier to understand and debug than more complicated digital fieldbuses, requiring only a handheld digital multimeter in most situations. Using fieldbuses and solving related problems usually requires much more education and understanding than required by simple current loop systems.