Product_description: ['The POSITAL IXARC OCD-EM00B-1413-C060-PRM Optical Ethernet ModbusTCP encoder provides 13 bit resolution and 14 bit resolution along with excellent dynamic response. A Ethernet ModbusTCP with TCP/IP, UDP, Modbus TCP (IEC 61158) profile offers the following programmable features: Resolution, preset, complement, transmission mode: polled mode, cyclic mode, change of state. Aluminum flange, Steel housing and void temperature range provide IP65 environmental protection. Since the rotation of the code discs is an entirely mechanical process, there is no risk of these devices losing track of their absolute position due to a temporary loss of instrument power. No backup batteries are required! A key component of optical rotary encoders is a code disk mounted on the encoder shaft. This disk is made of a transparent material that has a concentric pattern of transparent and opaque areas. Infrared light from an LED shines through the code disk, onto an array of photoreceptors. As the shaft turns, a unique combination of photoreceptors are illuminated or blocked from light by the pattern on the disk. For multiturn models, there is an additional set of code discs arranged in a gear train. As the main encoder shaft rotates, these discs are geared together to turn like the wheels of an odometer. The rotational position of each disc is monitored optically and the output is a count of the net number of rotations of the encoder shaft.'] (Page 1)