The index pulse is a very useful aspect of the machine.
Primarily, the index pulse is used to aid machine home.
The index pulse is one unique line on the encoder. It occurs one time in the entire revolution. It is a very special pulse indeed.
To turn on the index pulse functionality of a Techno Router:
- Click Setup
- Click advanced
- Click Homing params
- Check the box for Index next to all the axes. Read the warning and take it into account.
Note: Enabling the index pulse on the machine will slightly change the location of home on the machine. If you have a toolchanger or fixtures on the machine that are referenced with offsets, these spots will need to be re-learned.
When homing without the employ of the index pulse:
- The machine will home towards the end of travel until it finds the limit switch.
- After tripping the switch, it will back off until the switch is no longer actuated.
- After the switch is released, the machine home has been found.
- Due to the nature of limit switches, differences in approach speed, ambient temperature and age will * result in imprecision of the switch to the tune of anywhere from 0.0005″ to 0.002″.
- For most applications, this level of imprecision is acceptable.
- When this is too much imprecision, the index pulse is employed.
When the index pulse is being used:
- After backing off the limit switch until it disengages, the machine continues to move away from the switch until the index pulse is observed on the encoder.
- This pulse location is defined as the home.
- Now the system has homed to the resolution of the encoder/mechanics instead of the home switch.
A problem can exist wherein the index pulse is found very close to the home switch location (or one full turn away from the home switch). This results in a Home switch repeatability error.