Product Description:

The E4809-770-138-A is a motion-feedback interface board produced by Okuma for the E4809 CNC Boards series. Installed inside the servo cabinet of lathes and machining centers, the card links spindle and axis drives with the master control so velocity and torque loops remain closed for BL/PREX brushless motors. It decodes resolver and encoder signals, scales them for monitoring, and issues conditioned outputs that support accurate positioning and speed regulation in CNC equipment. Because the board sits between the feedback devices and the control system, it helps the machine interpret rotor position, speed, and load information in real time during cutting cycles.

Signal routing uses a female D-sub receptacle with 15 pins, which provides a compact connection point for the machine wiring harness. The hardware supervises 2 control axes and includes a two-character LED readout for local fault indication. Feedback excitation on the incremental channel is 3.3 V peak-to-peak, while the resolver winding is driven from a balanced source to reduce differential noise. Speed and torque feedback rails stay within ±3 V to protect downstream analog-to-digital converters, and resolver excitation is held at 6.0 V for consistent carrier injection across temperature changes. These voltage limits keep the feedback signals within the expected input range of the connected control circuits.

The speed monitor output is linear at 1562 rpm/V, providing a tachometer test point for checking commanded spindle rates. Encoder index channels are qualified by two minimum voltage thresholds: channel Z1 must exceed 1.4 V and channel Z2 must stay above 0.5 V, which helps suppress false zero-reference triggers in noisy environments. Torque monitoring is calibrated so that Peak Torque at 3 V corresponds to the full peak-torque reference, making overload conditions easier to identify before the servo amplifier reaches its current limit. The board handles reference, speed, and torque signals on the same assembly, which helps conserve back-plane space in dense servo cabinets.