Instruction manual

Introduction
28
890USE18300 September 2003
The Virtual Module
Summary Because reflex actions are designed to operate independently from the fieldbus
master, inputs to the reflex blocks generally come from local input modules. In some
applications, however, you may want the fieldbus master to provide an input value
to a block. One way to do this is via the virtual module.
The Advantys configuration software provides three words in the output process
image where the fieldbus master may write digital and/or analog values for use
exclusively as inputs to the reflex actions. These three words comprise the virtual
module.
Virtual Module
Structure
If you choose to use the virtual module, it may be one, two or three words in length:
If you want to use the virtual module only for digital inputs, the virtual module will
be one word long. It provides 16 bits where the fieldbus master can write up to 16
digital inputs to the reflex actions.
If you want to use the virtual module only for analog inputs, the virtual module will
be two words long. It will provide two words where the fieldbus master can write
up to two analog input values to the reflex actions.
If you want to use the virtual module for both digital and analog inputs, the virtual
module will be three words long. The first word provides 16 bits for digital inputs
and the second and third words are for two analog input values to the reflex
actions.
The word or words used for the virtual module are always the last words in the output
process image. If all three words are used, the digital word will appear first followed
by the two analog words.
Note: If you look at the vitrtual module data in the Modbus View of the Advantys
configuration software, the 16 bits of digital virtual data will be displayed in the low
bytes of two separate registers. If you look at the virtual module data in the Fieldbus
View, the 16 bits of digital virtual data may be displayed either in a single 16-bit
word or in the low bytes of two contiguous words, depending on the fieldbus. The
STB NMP 2212 Modbus Plus NIM and the STB NIP 2212 Ethernet NIM display
virtual digital data the way it is displayed in the Modbus View.