Portable dataloggers monitor analog I/O connections
ACR Systems’ SmartReader line of multichannel dataloggers addresses the need to monitor analog I/O connections without interrupting the process loop. When working with existing controls, the tendency is to place a 20 mA channel datalogger inline with the termination resistor. This can cause a ground loop when connecting to more than one channel if loops are not isolated.
ACR has posted an article on its Website that explains the advantages of using 2.5 V, 5 V, and 10 V channels. Dataloggers take a measurement at a predetermined interval and store the reading in the device’s internal memory for backup later. A single recorder running for 10 years on its own battery can store up to 1 million readings; information is then presented as a graph or exported with time and date stamp for further analysis.
A Control Engineering tutorial provides more help avoiding ground loops .