Hand Wheel

Most encoders used these days are incremental encoders which can only report changes in position not the absolute position. Hence for an encoder interface to track and report absolute position, the encoder counts must be correlated to a reference position in the mechanical system to which the encoder is attached. This is commonly done by homing the system, which consists of moving the mechanical system (and encoder) until it aligns with a reference position.

Homing is required whenever machine/controller restarts or when some machine parameters are changed.

Homing can be done in RA software either in JOG screen or RUN screen.

When an axis is not homed the position shown is prefixed with a '*', indicating that position is not correct, and axis needs to be homed.

When user enters RUN screen and axes are not homed, then 'Machine not referenced' message appears in the bottom right of the screen.

After reaching UDP without finding reference mark, "Press Down Pedal until RAM stops" appears as mentioned below:

When reference mark is found while RAM moves down, "Press Start Button" message appears as mentioned below:

In case the operator knows that RAM is above the reference mark and wants to avoid the default upward movement of the RAM then operator can force a change in homing direction by following these steps:

For machine operators

Hence operator must monitor the RAM when moving down and in cases where operator feels the reference pulse has not been detected despite RAM moving down significantly, operator must stop pressing down pedal. Operator must stop pressing Down pedal and press the emergency button, then release the emergency and press reset (Up pedal) to ON the pump, and again press reset (Up pedal). Now on pressing the start button, homing will start with RAM moving up (default homing direction).

RAM synchronization error

In some cases, due to unstable movement the Y1 Y2 difference exceeds the allowed Y1 Y2 difference and RAM Sync error occurs and RAM cannot be moved in RUN or JOG mode. In these cases, it is required to login to machine parameters with service access level and enter diagnostic mode and manually move the RAM, hence operators cannot handle this error on their own. Hence in RA there is a feature provided which forces homing to happen for Y1 Y2 (without restarting the machine), so that operators can handle RAM sync error without resorting to service person.

As homing when RAM position is above the reference mark is a two-step process, it is advised to lower the RAM before restarting or powering off the machine in order to complete homing quickly when machine is powered on next time.

Generally, when the homing command is activated, all the backgauge axis will start to move in the homing direction (Safe direction, selected in homing parameter). If the backgauge is near to the tools during homing, then the movement of the R - axis may result in collision with tools. In order to avoid this type of collision the X-axis will be homed first with Sequence number as 1 (default value of parameter) and other R & Z axis will be sequence number 2 (default value of parameter), to follow the homing process.