Rockwell Automation 1788-CN2FF ControlNet-to-FOUNDATION Fieldbus H1 Linking Device User Manual - Manual (Page 31)

1788-6.5.1 - January 1999
Using the ControlNet-to-FOUNDATION Fieldbus H1 Linking Device 4-5
Figure 4.3 Alarm Attribute Definition
Bits 7-3, DON’T CARE, are undefined when read and should be ignored
when performing a GET. The DON’T CARE bits should be written as 0
when performing a SET. Bit 2, Acknowledge, is undefined when read and
should be ignored when performing a GET. When a user wants to
Acknowledge an alarm, this bit should be written as a 1 when performing a
SET. Each time the LD detects a 1 in the Acknowledge position, a Fieldbus
Acknowledge will be generated. Therefore, users must be careful not to set
the Acknowledge bit more than once per alarm. Bits 1 and 0, CLEARED
and ACTIVE respectively, are read/write bits. When an alarm condition is
ACTIVE or CLEARED, these bits are read as a 1 when performing a GET.
The user must Confirm each of these states by writing them to a 0 by a SET.
Once an alarm has occurred (become ACTIVE), alarm processing is NOT
complete until the user intervenes to remove the alarm condition,
Acknowledges the alarm (writing a 1 in the Acknowledge bit position),
Confirms the alarm (writing a 0 to the ACTIVE bit position once it is read
as a 1), and Confirms the alarm condition being CLEARED (writing a 0 to
the CLEARED bit position once it is read as a 1).
Analog Outputs This section describes configuration of the linking device to control any
analog value (and status) in a Fieldbus device, such as in a Analog Output
(AO) function block. It also describes the attributes of the created
ControlNet analog output object.
The linking device contains a number of MAO block instances. Each
instance of the MAO block is the software equivalent of an analog output
module in an I/O subsystem. Each MAO block also has eight channels or
outputs, with each channel containing a float and a status pair. Each MAO
block has eight inputs to provide for the BKCAL or readback from the
analog output function blocks. The linking device assigns a tag to each
MAO block in the form CNetMacId
xx_AO_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 Outputs
The NI-FBUS Configurator lists all the devices and the function blocks in
each device in its browse window. This includes the AO function blocks in
the Fieldbus devices and the MAO function blocks in the linking device.
You must connect the Fieldbus AO function blocks that will be controlled
by the ControlNet controllers (or devices) to the MAO channels.
Bit Position
Value Acknowledge CLEARED ACTIVE
0 1 2 3 4 5 7 6
X X X X X