Siemens SIMATIC FM 351 - Page 64

Machine Data and Incremental Dimensions
8-4
FM 351 Positioning Module
C79000-G7076-C351-02
Reading incremental dimension tables
To read the incremental dimension tables from a channel, follow the steps outlined
below:
• Set the trigger bits in the channel DB for the following jobs:
– Read incremental dimension table 1 (TRGL1RD_EN) and / or read
incremental dimension table 2 (TRGL2RD_EN)
• Call the FC ABS_CTRL function in the cyclic user program.
The incremental dimension tables are stored in the parameter DB on the CPU.
Excerpt from the Channel DB
Address Name Data
Type
Initial Value Description
35.4 TRGL1WR_EN BOOL FALSE 1 = write incr. dim. table 1 (1 ... 50)
35.5 TRGL2WR_EN BOOL FALSE 1 = write incr. dim. table 2 (51 ... 100)
36.6 TRGL1RD_EN BOOL FALSE 1 = read incr. dim. table 1 (1 ... 50)
36.7 TRGL2RD_EN BOOL FALSE 1 = read incr. dim. table 2 (51 ... 100)
Note
If parameters are modified that are relevant for the synchronization, the following
actions are taken by the module for the relevant channel when the machine data
are activated:
• Synchronization deleted
• The function switches and zero point offset are reset
• All previous machine data and incremental dimension tables become invalid
The following parameters are relevant for synchronization:
• Axis type
• End of rotary axis
• Encoder type
• Displacement per encoder rev.
• Increments per encoder rev.
• Number of revolutions.
• Reference-point coordinate
• Absolute encoder adjustment
• Type of reference point approach
• Count direction