QUESTION:
How is the handwheel on the Mobile Panel 170 configured?

ANSWER:  
The handwheel can only be used when the Mobile Panel 170 is operated on the PROFIBUS-DP. For evaluating the handwheel, the DP push button functionality for the Mobile Panel 170 must be configured. The directional impulses of the handwheel are deposited in two bytes in the process image of the CPU. The byte addresses depend on the addresses that have been declared in the STEP 7 hardware configuration of the module "Mobile Panel 170". The bytes must be queried cyclic on the control side within one second. Each impulse of the handwheel is added to the appropriate byte (n+3 for the forward impulse or n+4 for the backward impulse) according to the rotating direction.

The handwheel configuration is explained with an example project which you can download free of charge. The example covers the calculation and the analysis of the handwheel position on Mobile Panel 170.

Configuration of the hardware: 

• Create a STEP 7 project.
• Prepare your STEP 7 hardware configuration. Please make sure that the PROFIBUS-DP connector on your CPU is networked.
• Insert a SIMATIC OP "Mobile Panel 170" in your STEP 7 configuration, provided that you use ProTool-integrated.
• Open the ProTool project and apply your settings for the control connection. The Mobile Panel 170 must be configured on the PROFIBUS-DP.
• Save and close the ProTool project. Change to the STEP 7 hardware configuration.
• Open the hardware catalog and choose PROFIBUS-DP > Configured Stations > SIMATIC OP > OP170 / TP170B / Mobile Panel 170 Keys. Append this station to the PROFIBUS-DP of the CPU.

Figure 1: Hardware Catalog - configured stations

• Integrate the module "Mobile Panel 170" and adjust the in- and output address of the module.

Figure 2: Hardware catalog - Module: Mobile Panel 170

• Save and transfer the configuration.

Figure 3: Inserting the Mobile Panel 170

• The hardware configuration is now completed.

Description of the STEP 7 program:
The STEP 7 program contains a FB (FB 11) with the appropriate instance DB (DB 11) for the analysis of the handwheel position and a OB (OB1) with the requested FB. 

The FB 11 is structured in four networks.

• The first network evaluated a reset signal. If this signal is set, the handwheel position is set to 0 in this position. At the end of the network, the signal is reset.
• The forward impulse of the handwheel is analysed in the second network. By comparing the number of current forward impulses of the handwheel (in this case PEB3) and the previous number of forward impulses, it is calculated if the handwheel has been turned forward. If this is the case, the difference between the two values is stored. This value is the old impulse value for the next cycle and is needed for calculating the absolute position of the handwheel.
• The third network analyzes the backward impulse of the handwheel. Basically, this network operates according to the same principle as the second network.
• The fourth network is needed to calculate the absolute position of the handwheel. This value is calculated by the continuous addition of the difference between the forwards and backwards impulses.

Description of the ProTool project:
The ProTool project serves the visualization of the handwheel position in a output field and the generation of a reset signal by a keystroke.

Further information regarding the configuration of DP direct keys on the Mobile Panel 170 can be found in the manual of the MP170 in entry ID ID 13506223.

The example was created with STEP 7 V5.1 SP6 and ProTool Pro CS V6.0 SP2. It contains the functions described above.

 handwheel.exe ( 346 KB )  

Copy the file "handwheel.exe" in a separate directory. Unpack the STEP 7 project with the integrated ProTool project with all appropriate subdirectories. Afterwards, you can can open and edit the unzipped project with the SIMATIC Manager.