What the part is
The Omron R88ACRKC020NRE is a 20m servo motor encoder cable listed for use with the Omron G5 Servo Motors family, and it is the factory-defined length variant within the R88ACRKC encoder-cable line. Its role on the machine is the feedback leg between the servo amplifier and the motor-mounted incremental encoder — the cable that carries position pulses back to the drive so the position loop closes cleanly. Servo encoder cables of this class are specced and terminated by the drive maker, not field-terminated: the jacket, shield termination, and connector pinout are matched to the G5 amplifier side so the loop closes without re-pinning.
Where it sits in the BOM
On a G5 cell the encoder cable is called out alongside the power cable and the brake cable as a matched accessory set; the 20m figure is the maximum practical reach most builders allow before they look at a repeater or a different layout. For longer cable runs the usual failure mode is feedback noise and position-error faults, not cable damage — which is why the factory cable, with its defined shield construction, is preferred over a generic twisted-pair substitute.
Lifecycle and sourcing posture
For a Tier-1 line that needs full part genealogy on the bill of materials, ordering against the Omron order code — not a third-party equivalent — keeps the cable traceable to the same supplier chain as the drive and motor it lands on.