Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules User Manual
Page 116
116
Rockwell Automation Publication 1756-UM533C-EN-P - February 2011
Chapter 7
Configure the Modules with RSLogix 5000 Software
The module collects the PV, SV, TV, and FV data as described in
.
Command 3 does not provide PVStatus, SVStatus, TVStatus, or FVStatus, so
HART devices that indicate Command 3 as shown in
will have their
Dynamic Variable Status values reported based on the communication status with
the HART field device. If the Dynamic Variables are being collected without
communication error, the Status value is 16#C0 (2#11000000), which means
good. Otherwise, it is 0, meaning bad.
Some devices don't have four dynamic variables. In this case, they can report a
NaN value to indicate they have no valid value for that parameter.
The dynamic variables do not update as fast as the analog signal. The actual rate
depends on the number of channels configured for HART (for the
8-channel modules), the number of pass-through message commands, the
presence of handheld communicators or other secondary masters, and the
response speed of the field device.
When eight channels are in use on the 8-channel modules, the HART update rate
is in the 10-second range.
Table 30 - Dynamic Variable Assignment
(1)
(1)
Table does not apply to the 1756-IF8H and 1756-OF8H modules, version 1.x , and the
1756-IF16H module, version 1.1
HART
Version
HART Device Reports
PV, SV, TV, FV
Assignments in
Command 50
HART Command Used
by 1756 Module to
Collect PV, SV, TV, FV
Device Variable
Codes Used in
Command 9 for
PV, SV, TV, FV
5
N/A
3
N/A
6
No
3
N/A
Yes
9
As Reported in
Command 50
7 or later
No
9
246, 247, 248, 249
Yes
As Reported in
Command 50
IMPORTANT
Verify that the actual HART update rate is appropriate for your
application. Remember that pass-through message traffic, additional
status information, secondary masters, and communication errors can
delay the update rate. Note that on the 8-channel modules, because the
HART modem is shared by all channels, increased delay on one channel
affects other channels also.
IMPORTANT
Verify that HART data is valid by checking ChxFault, HARTFault, and
values such as PVStatus and SVStatus.