I purchased an isolator, and a resistor came with it. What is the resistor used for?

F Series signal conditioners are compact, space-saving (24 mm width) signal conditioners with front panel terminals. The microprocessor based models provide field configuration capability and minimum stock of spares. The installation is either DIN-Rail, Rack or Wall mounting, and the power supply is 24 V DC.

Compact size, versatile mounting, and microprocessor based high performance capabilities makes the W Series an excellent choice for almost every application. The specifications of W Series signal conditioners are as same as F Series signal conditioners except for power supply voltage, second output and case width.