Rockwell Automation 1788-CN2FF ControlNet-to-FOUNDATION Fieldbus H1 Linking Device User Manual - Manual (Page 38)

1788-6.5.1 - January 1999
4-12 Using the ControlNet-to-FOUNDATION Fieldbus H1 Linking Device
Discrete Outputs This section describes configuration of the linking device to control any
discrete value (and status) in a Fieldbus device, such as in a Discrete Output
(DO) function block. It also describes the attributes of the created
ControlNet discrete output object.
The linking device contains a number of MDO block instances. Each
instance of the MDO block is the software equivalent of a discrete output
module in a I/O subsystem. Each MDO block also has eight channels or
outputs, with each channel containing a byte and a status pair. Each MDO
block has eight inputs to provide for the BKCAL or readback from the
discrete output function blocks. The linking device assigns a tag to each
MDO block in the form CNetMacId
xx_DO_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 Discrete Outputs
The NI-FBUS Configurator lists all the devices and the function blocks in
each device in its browse window. This includes the DO function blocks in
the Fieldbus devices and the MDO function blocks in the linking device.
You must connect the Fieldbus DO function blocks that will be controlled
by the ControlNet controllers (or devices) to the MDO channels.
The MDO function block has two valid configurations. In the first
configuration the BKCAL_OUT_D parameter of the DO is not connected
back to the controller. In this case, there is no mode handshake provided by
the upstream controller for cascade initialization of the DO. You connect
only the CN_OUT_D
x parameter from the MDO to the CAS_IN_D of the
DO block. In this case, you must not connect the BKCAL_OUT_D
parameter of the DO to the BKCAL_IN
n parameter of the MDO block.
Figure 4.9 Sample Cascade DO Configuration