Axis flags used for limit monitoring are updated every 50 milliseconds by default. These flags include:
If needed, the update rate of these bits can be increased to the Servo Period update rate. The Fast Update rate is activated in a two step process.
- The bits which are to be updated quickly are selected via the "Fast Axis Limit Flags" selection in "Secondary Axis Flags"
- The Fast Update Mode is turned On or Off via Bit 5632 "Enable Fast Flags Update Mode" in the "Miscellaneous Control Flags"
Once this process is completed, the Axis Limit Flags (E.G. Bit 768, Bit 866, etc.) will update every servo period.
Visually, this can be thought of as the chart below:
The individual bits control whether or not a specific flag is selected for fast updates, and bit 5632 selects whether or not the Fast Update Mode is On or Off. Having a single bit to turn Fast Update mode on and off allows simpler control of this feature as it is processor intensive. A user can select all of the bits they need for fast update once, and then use Bit 5632 to activate or deactivate the entire Fast Update mode.
Notice on the right of the chart above the Group labels. Each type of axis flag (for example: Fast IPB flags) is considered a Group. Only one Group of axis flags is updated each servo period. For example, if Bit 2328 (Group 0), Bit 2329 (Group 1), and Bit 2361 (Group 1) are set and Fast Updates are enabled (Bit 5632), then the EXC Flag for Axis 0 (Bit 769) will be updated during the first servo period, and the IPB flags for Axis 0 (Bit 769) and Axis 1 (Bit 800) will be updated the next servo period.
Example: A user would like to precisely monitor the "Not In Position (IPB)" bits of Axis 0 (Bit 768), Axis 2 (Bit 832), and Axis 3 (Bit 864) as well as the "Not Torque Limit TLM" bit of Axis 3 (Bit 868). To do this the user would refer to chart above for which bits to set. The image below shows which bits are set in red.
Once these bits are set, the updates to the Axis Limit Flags will occur as follows:
- Servo loop update #1: Not In Position (IPB) bits of Axis 0 (Bit 768), Axis 2 (Bit 832), and Axis 3 (Bit 864) will be updated (Group 0)
- Servo loop update #2: Not Torque Limit (TLM) bit of Axis 3 (Bit 868) will be updated (Group 1)
- Servo loop update #3: Not In Position (IPB) bits of Axis 0 (Bit 768), Axis 2 (Bit 832), and Axis 3 (Bit 864) will be updated (Group 0)
- Servo loop update #4: Not Torque Limit (TLM) bit of Axis 3 (Bit 868) will be updated (Group 0)
This process will repeat continuously until Bit 5632 is cleared, or the individual bit selections are cleared.
VL 2021-03
