Multifunction Data Acquisition Devices Combine Safety and Accuracy

Built-in isolation increases the safety of data acquisition devices and eliminates common problems that can ruin measurement accuracy. The new multifunction devices offer 16-bit accuracy, 250 kS/s sampling rates, ±10 V or ±20 mA analogue inputs, ±10 V or 0-20 mA analogue outputs and 5 V TTL/CMOS or 24 V digital inputs and outputs.

The new isolated M and S Series devices offer channel-to-channel or bank isolation with 1,950 VDC/1,400 Vrms transient withstand for 5 s to a PCI bus, which protects expensive equipment, the user and data from hazardous voltage spikes, transient signals and electrical noise. Isolation works by electrically separating the circuit’s front end, where hazardous voltages can exist, from the rest of the data acquisition system. Isolation is especially important when taking measurements from sensors in the proximity of wall power, large motors, high-voltage switches or other high-voltage lines.

Isolated M and S Series devices also reject common-mode voltages and prevent ground loops from forming, eliminating two common problems for data acquisition system users. High common-mode voltages can make it impossible to measure the signal in a non-isolated data acquisition system and can even damage the system. The new isolated M and S Series devices can measure from sensors with the signal plus common-mode voltages of up to 60 V. Ground loops, which occur when there is a difference between the ground voltages of the measurement system and the signal being measured, can result in high currents flowing between the two grounds and can damage equipment and ruin accuracy.