Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 162)

Publication 1757-UM006A-EN-P - May 2002
7-2 Using the 1788-CN2FF, ControlNet-to-FOUNDATION Fieldbus H1 Linking Device
Analog Inputs This section describes configuration of the linking device to access
any analog value (and status) in a Fieldbus device. It also describes
the attributes of the created ControlNet analog input object.
The linking device contains two of MAI block instances on each
Fieldbus channels. Each instance of the MAI block is the software
equivalent of an analog input module in an I/O subsystem. Each MAI
block has eight channels, with each channel containing a float and a
status pair. The linking device assigns a tag to each MAI block in the
form CNetMacIdxx_AI_Modulei-j, where xx is the ControlNet network
address, i is the Fieldbus channel number, and j is the module or
instance number.
Configuration of Analog Inputs
When the NI-FBUS Configurator is started, and continuously
thereafter, it lists all the devices and the function blocks in each device
in its browse window. This includes the AI function blocks in the
Fieldbus devices and the MAI function blocks in the linking device.
You must connect the Fieldbus AI function blocks that will be
accessed by ControlNet controllers (or devices) to the MAI channels,
as shown in Figure 7.1.
Figure 7.1 Sample Single Macrocycle MAI Configuration
The NI-FBUS Configurator sets up the analog input devices to publish
their data on Fieldbus. The linking device MAI block subscribes to
these values and produces them on ControlNet. Each MAI block has
its own schedule of subscribing on Fieldbus and producing on
ControlNet. For different rates (macrocycle) of production on