Required vs Optional Axis Attributes

In the attribute tables, attributes and services are defined as Required (R) or Optional (O). Required attributes and services must be supported in the implementation of the object. Optional attributes and services may or may not be supported in the implementation and are left to the discretion of the device manufacturer.

For Instance Attributes, the determination of whether a given attribute or service is Required or Optional often depends on the associated Device Function Code.

Required Implementation

If an attribute is marked as Required for a given Device Function Code, then the controller implementation, including configuration and programming the software, support that attribute if the end device is intended to operate in that mode. For example, an attribute marked as Required for Device Function Code 'V' is supported by any controller that intends to interface to a CIP Motion device that supports Velocity Loop operation.

In some cases, an attribute or service may not even be applicable to a given Device Function Code. This situation is implied when the attribute is defined as neither Required nor Optional for that code. The Required and Optional classification of a given attribute can therefore be used in configuration software design to determine if the attribute is applicable and requires user entry.

Conditional Implementation

For some attributes, there are conditional implementation rules that extend beyond the Device Function Code. These rules are specified in the Conditional Implementation column of the following table. In the following example, the attribute PM Motor Resistance is Required “R” in the implementation if the device supports Frequency Control, Position Control, Velocity Control, or Torque Control and the device supports Permanent Magnet motors, that is, “PM Motor only”. The attribute is Not Applicable “-” for a Bus Power Converter or a Feedback Only device or a drive that does not support a PM motor.

To get details about how to specify the attribute, refer to the attributes list for the functional category. For this example, PM Motor Resistance is a member of the General Permanent Magnet Motor Attributes category. The following table provides an example of the details:

When you are reviewing the tables for an attribute remember that Vendor-Specific attributes, attribute enumerations, and bits, are Optional by definition. Attributes that have Optional enumerations or bitmaps are designated so in the Condition Implementation column. Details about Optional and Required support for the individual enumerations or bits for these attributes can be found in the detailed attribute behavior tables.

The software queries the specific drive profile, Add-on Profile (AOP), to determine if the Optional attributes listed in the table are supported. Attributes that are marked with an AOP in the Conditional Implementation column have semantics with additional, drive specific, optional behavior that is queried.

If the conditional implementation column reads "Derived", it means that the value for an attribute is determined (derived) by the controller based on the value of another attribute. In this case, the current attribute follows the conditional implementation rules of the attribute from which it is derived. Derived attributes do not need to be downloaded to the controller but must be supported by setting the appropriate bits in the Drive Set Attribute Update Bits attribute, if applicable.

Conditional Implementation Key

The following table identifies the key abbreviations used in the conditional column of the attributes tables and provides a description of the condition it represents.