Retrofit of a Gluing Station using SIG200, SIG100, MPA and SLT for Fill Level Visualization

The general purpose of the gluing station is to glue parts of the sensors KTX, KTS and CSS. Pictures of the application are shown at the end of this report.

The retrofit is divided into the cartridge fill level visualization and the presence detection of objects with different surface characteristics using one W4 sensor, which is shown in another tutorial. The general schematic plan is shown as follows.

The gluing is automated by two pneumatic cylinders which press on each (two) adhesive cartridge. Before the retrofit, the fill level was monitored by using two standard cylinder sensors for the level nearly empty and empty. By replacing both with an IO-Link MPA sensor (on each pneumatic cylinder), more functionalities can be achieved. To measure the cartridge fill level, the current position of the cylinder was mapped (using the SIG200 logic editor) to the 0 to 100% fill level and visualized with the SLT signal lights mounted on top of the gluing station. The before used switching positions for nearly empty and empty were logically configured and assigned to the correspondingly used output ports of the SIG200 or SIG100 (see schematic plan). The digital outputs are again used in order to not change the old PLC program.

• The logic is divided in two main parts. The main part "MPA & SLT" (blue dashed frame) is divided into the parts "Scaling" and "SLT Alarm Output Config.". The second part indicates the configuration of the "W4" functions (green dashed frame).
• Numbers written in purple indicate the value of a constant.
• Text written in red indicate a variable for the further explanation

• Outputs
  • O1 is the user defined alarm of the SLT
  • O2 is the level of the SLT (in level meter mode)
  • O3 is Port 1 of the SIG100, which is defined as output
  • O4 is Port 2 of the SIG100, which is defined as output
  • O5 is Port 3 of the SIG100, which is defined as output
  • O6 is Port 4 of the SIG100, which is defined as output

• MPA & SLT

• General: The used negation blocks in the picture below are used in order to be safe against broken cables.
• 
  Scaling
• The scaling procedure results in O2, which is the level scaled from 0...100 % of the SLT (port S3). The input of the part is the position of the MPA sensor in millimeters.
• The flow illustrates the following formula:

• • I1 is the position of the cylinder measured by the MPA sensor
  • C1 is the offset of the cylinder where the scaling is 0%
  • C2 equals 100 %
  • C3 is the raised position (max. position for the application) of the pneumatic cylinder

The last subtract block (right) is to get the difference between the current level in percent (out of the divide block) and 100 %. This is necessary for the intended light behavior of the SLT light, where 0 % indicates "empty cartridge" and 100 % "full cartridge".

SLT Alarm Output Config.
The previously used cylinder sensors for empty and nearly empty have also been replaced by the MPA sensor. To do this, the percentage level of the divide block (hereafter referred to as div_level) from the scaling section was used and the levels for empty (C5) and nearly empty (C4) were defined. The corresponding positions/level represent the before mounted cylinder sensors.

• • If C4 is lower-equal the div_level XOR If C5 is lower-equal div_level, the negated output O5 is switched
  • If C5 is lower-equal div_level, the negated output O6 is switched
  • If C5 is lower-equal div_level, then O1 is C6 (Alarm 1), else C7 (0 - no alarm)

The XOR block causes, that O5 is switched as long as O6 is not switched and the div_level is greater than C4. This means that if the div_level exceeds the nearly empty level, negated O5 is switched. But if the div_level raises more (greater than C5), O5 is reset and just the negated O6 is switched.

The configuration of the second MPA & SLT combination is similar to the first one. Only the constants are different. For the explanation, please take a look at the first SIG200 Logic Editor configuration.