Siemens 500 NIM User Manual

NIM Primitives

Primitives are high-level commands that allow a user to access like data
types in all different Secondaries in the same manner.  For example, a
Primary can access image register memory in a NIM-equipped 520, 530,
5TI, and PM550 controller with the same command. The purpose of the
Primitives is to remove as many differences as possible between the
controllers, so that applications programs at the Primary level may treat all
TIWAY I Secondaries in the same manner.

Primitives provide the following benefits.

•

Primitives reduce the amount of host computer software needed to
acquire data from the Secondaries.

•

Primitives provide a standard communication protocol that allow you to
communicate with different types of secondaries and attached devices
without custom software routines.

•

Primitives allow more efficient use of the available network bandwidth
by increasing the amount of data that is available in a single message.
For example, with a single programming peripheral Task Code, you
might be able to access no more than 15 words of data. With some
Primitives, up to 134 words can be accessed.

•

Primitives reduce total system loading. This is possible because the
NIMs can memorize data locations that are repeatedly accessed. Block
and Record Gather Primitives make it possible to access a block of data
previously defined and stored in the NIM.