Basics; Recording Weight As Measured Variable And Providing As Value - Siemens SIMATIC S7-1200 Manual

3 Basics

3.1 Recording weight as measured variable and providing as value

Basics
3
3.1 Recording weight as measured variable and providing
as value
Table 3-1
No.
1. The SIWAREX WL260 load cell is used to
convert a mechanical force into an electrical
signal.
Four expansion measuring strips (EMS)
interconnected to a Wheatstone bridge, are
attached to the spring rod of the load cell.
2. If a force acts upon the spring rod and
compresses or stretches the expansion
measuring strips attached to it, an overall
misalignment of the spring rod can be
determined from the positive and negative
changes in resistance. (Measurement voltage,
proportional to change in resistance)
3. With the aid of the analog-digital converter
integrated in the SIWAREX WP231 weighing
module, a weight value is continuously
calculated from the measurement voltage.
4. The S7-1200 controller accesses this weight
value via the backplane bus in the analog input
address area of the WP231 weighing module.
The transferred value is a 16-bit integer value.
The "WP231PR" function block is used for the
conversion into the respective weight value as
floating point number.
The weight value to be used is stored in the
"WP231PR_DB" instance data block.
Weighing, Controlling and Logging (Set 6)
Entry ID: 82454336, V2.0,
Function
10/2017
Comment
DMS (gestreckt) DMS (gestreckt)
DMS (gestaucht) DMS (gestaucht)
DMS DMS
DMS DMS
(gestaucht) (gestaucht)
(gestreckt) (gestreckt)
belasteter Biegestab belasteter Biegestab
gestreckter gestreckter
gestauchter gestauchter
DMS DMS
DMS DMS
gestauchter gestauchter
gestreckter gestreckter
DMS DMS
DMS DMS
Measuring signal
Weight
2300 g
value
10 ms
WP231PR
WP231PR_DB
Prinzipdarstellung Prinzipdarstellung Prinzipdarstellung
einer einer einer
Wheatstone-Bridge Wheatstone-Bridge Wheatstone-Bridge
F
Weight
value
11