Evaluating The Technology Data Block - Siemens SIMATIC S7-1500 Function Manual

7.2.2

Evaluating the technology data block

Description
Access to data in the technology data block occurs in accordance with the access to
standard data blocks.
Reading values from the technology data block
In your user program you can read actual values (e.g. current position) and status
information, or detect error messages in the technology object. When you program a query
in your user program (e.g. current velocity), the value is directly read from the technology
object.
Reading values from the technology data block takes longer than for other data blocks. If you
use these tags several times in a single cycle of your user program, it is recommended to
copy the tag values to local tags, and use the local tags in your program.
Writing values to the technology data block
The configuration of the technology object in the TIA Portal is used to write the
corresponding data to the technology data block. After they have been loaded into the CPU,
these data are stored in the CPU on the SIMATIC Memory Card (load memory).
● Required changes in the technology data block
● Effectiveness of changes in the technology data block
S7-1500 Motion Control V13 Update 3
Function Manual, 07/2014, A5E03879256-AC
In the following cases, it may be necessary for the user program to write values to the
technology data block:
– Adaptation of the configuration of the technology object (e.g. dynamic limits, software
limit switches)
– Use of overrides
– Adaptation of position control (e.g. "Kv" parameter)
Changes to values in the technology data block by the user program can take effect at
various points in time. The relevant property of the individual tags can be found in their
descriptions in the Appendix (Page 332).
– Effective immediately:
LREAL data type
(e.g. <TO>.Override.Velocity)
Value changes take effect immediately when writing these tags. The technology object
performs a range check on the written value, and immediately starts using the new
value. If range limits are violated when writing, the technology object automatically
corrects the values. If the value is below the range, then the value is set to the lower
limit of the range; if the range is exceeded, then the value is set to the upper limit of
the range. You write changes using direct assignments. The changes are retained
until the next POWER OFF of the CPU or restart of the technology object.
Programming
7.2 Technology data block
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