User Units in the PDMM
One of the commonly asked questions when programming a KAS based controller is how to setup user units. User units are defined in the section of the project tree:
Expand the section of the project tree, then the PLCopen motion section, right click on one of the axes, and select “Property”. For each motor axis in defined in the application there is an axis data section in which the number of User Units per Drive Interface Units can be specified:
The Drive Interface Unit default is 1048576 IU (Internal Units) and this corresponds to one rev of motor motion (360 degrees) or with a linear motor the distance of one magnetic pole pair (32 mm with most Kollmorgen motors). The user is able to create user units in the units desire (mm, cm, mils,etc). For more detail and examples see this section in the KAS IDE online help: Using KAS IDE > Creating a Project > Step 12 - Adding Motion > Motion with PLCopen > Modify PLCopen Axis > Axis Data Parameters
Expand the section of the project tree, then double click on ‘PipeNetowrk” to open up the pipe network editor. For each axis in the project there will be an axis block.
Right click on the axis block then select Properties and finally select the parameter tab:
The USER_UNITS_PER_REVOLUTION field allows the user to create user units in the units desire (mm, cm, mils,etc). If using a linear motor then USER_UNITS_PER_REVOLUTION will actually be USER_UNITS_PER_POLEPAIR. In the example above Users units for position would be in degrees since the value is 360 UU per motor rev.
The user units set up will then apply to all motion related Function Blocks in the KAS function block library.
Units for Speed and Acceleration parameters:
- Speed Parameters using as inputs in KAS function blocks are in units of User Units/Sec
- Acceleration Parameters using as inputs in KAS function blocks are in units of User Units/Sec2
- Jerk Parameters using as inputs in KAS function blocks are in units of User Units/Sec3
Note: The AKD Workbench Units screen is not used for setting up user units in a KAS application
Online configuration mode is used for setting up drive related functionality such as tuning, motor model, certain I/O functionality, limits, etc. The Workbench screens built into the IDE are used for this task. For example see the Scope screen below.
In the Workbench screens the default units for speed and acceleration for rotary motors are:
- Speed Parameters are in units of RPM (Rev/Min)
- Acceleration Parameters are in units of RPM/Sec
For linear motors, the units for speed and acceleration are:
- Speed Parameters are in units of Counts/Sec
- Acceleration Parameters are in units of Counts/Sec2
It is possible to change the default units in the Parameters screen to make the units just like the Controller units or to something similar:
Making this change will affect units shown in the Scope and other screens. For example after changing the user units to cm, position based parameters in the Limits screen are now in terms of cm: