A strain gauge sensor system and method for measuring the strain in a member, such as a fiber rope, has a sensor target assembly having a plurality of magnets carried spaced apart by individual gauge lengths along the member. Position and trigger sensor devices are configured spaced apart along side a desired path of travel of the member. When the member is fed along the desired path of travel, the trigger sensor device, in response to magnetically sensing a passing magnet, triggers the position sensor device to read the position of an adjacent passing magnet. The strain in the gauge length is determined from the read position. RFID tags placed on the member between the magnets can be identified by an RF reader to identify a particular gauge length being measured. The system can include a deployment device for feeding the member along the desired path.