NOTE: This product has been moved to the Obsolete Archive.
Over the past few years, the need for a device to turn off the servos but retain encoder position has gained popularity.
IAI has provided a solution for this problem and has called it the "Servo Relay Box". The Servo Relay Box consists of one relay per axis (up to two axes per box) and an additional timer relay to handle the controller. In addition to this, the user receives specialty cables that split the motor, encoder and brake wires.
The Servo Relay Box is not currently available on any other controller than the SuperSEL E/G Series. It is available as a one axis or two axis unit. Any more than two axes and multiple Boxes must be purchased.
The diagram above shows a typical two axis wiring scheme in order to use the Servo Relay Box.
Wiring of the system using the Servo Relay Box is simple. Special cables run between the actuators and the Box, and then from the Box to the controller. The critical fact involved with this wiring is that the encoder wires run uninterrupted between the actuators and the controller and will retail their information as long as the controller is up and ready.
The "EMG" connection is a generic label as it can be used for a light curtain, door interlock or any other safety device. As you can see, this is also tied to one of the SuperSEL controller inputs for purposes of program control. The Servo Relay Box handles the physical disconnection of the motor, but a program inside the controller must be running in order to tell the controller to stop looking for the servo.
Since the SuperSEL controller can have multiple programs running concurrently (multitasking) a separate program can be running to monitor the Servo Relay Box. When this input is "tripped" or turned on, the monitor program stops the motion program in order to have a clean break. Remember, the controller will still think the servo is operating as normal if this program is not running concurrently.