1. Is
special installation software needed to configure the module? What
about the field device?
Module installation is supported from RSLogix 5000 programming
software and is similar to standard analog modules. The user can
simply create a generic profile for the Module and RSLogix
allocates the correct number of registers for communication, If
the end user uses the sample ladder, available on the Web site, it
is just a simple matter of copying and pasting.
Configuring field devices can be accomplished by sending HART
messages from the PLC to the field device using the HART module as
a bridge. The end user can then utilize a standard operator
interface to select the desired HART command. and then execute the
command. The end user can use a SCADA package, Microsoft Excel or
PanelViews to accomplish this task.
2.
Can the Analog I/O HART Module be used with Ethernet or ControlNet
networks? If so, is a PLC required if an Analog I/O HART module is
used in a remote Ethernet or ControlNet drop?
Yes. The module
can be used in a remote Ethernet or ControlNet chassis. Spectrum
Controls has created, tested and made available the EDS files to
allow this type of connection. There does need to be at least one
owner PLC in the system; however, the owner PLC can reside on any
ControlNet or Ethernet network in the system.
3.
Do
I still need a hand-held communication device with the Analog I/O Module with HART?
No. Each module also acts as a HART
master, allowing communication with HART field devices. Field
devices may be interfaced directly to the module, eliminating the
expense of additional external HART bridge devices or hand-held
communicators. Although it is possible to use a hand-held
communicator in conjunction with the module, it is not
necessary.
4. Can
I use an HMI or SCADA interface to configure field devices?
Yes. An
HMI or SCADA package can access the field devices through the HART
modules by either sending a CIP message or by passing the data
using program tags.
5. Does
the I/O support multi-drop HART applications?
No. The
module does not support this function.
6.
If the module is communicating via the 4-20mA signal, can it also
acquire HART data at the same time?
Yes. HART Protocol allows the
simultaneous communication of the continuous 4-20mA as well as a
second digital communication path resting on top of the analog
signal, but not interfering.
7. What
kind of field devices are HART-enabled?
Most
smart field devices are HART-enabled—from mass flowmeters to
valves. Check with the device manufacturer.
8.
What
field devices are compatible with the Analog I/O Modules with HART
Protocol?
Any
HART-enabled device is compatible. The Spectrum Controls Analog
I/O Module with HART Protocol is not device specific.
9. What
kind of data will I receive from the HART device?
Process
variable values, status and diagnostic, calibration and ranging
information and device specific information.
10.
Can
I perform diagnostics? Set alarms?
Yes and
yes. You can also perform other functions remotely, such as
commissioning.
11.
Is
HART communication fast enough to be useful in process
control applications?
The analog 4-20mA signals are available full time to address the
needs of fast changing or critical process measurements. Data to
support multivariable measurements, remote diagnostics and device
status can be accessed digitally while the analog signal is being
used for control.
12.
Are
there any issues on how the data is displayed within the PLC?
Floating point
values sent or received from the module through the PLC are
reverse. The HART Protocol supports the IEEE-754 Single Precision
Float where as the PLC supports the Reverse IEEE 754 Single
Precision Float. Two rungs of ladder are required to correct the
order of the data contained in the floating point value.
13.
How do you obtain the device specific
commands for a given HART device?
Although the HART modules support he device specific
commands, the device manufacturers do not publish this
information. Therefore, the end user must obtain the device
specific commands directly from the manufacturer of the HART
device in question.
14. What is the longest update time that can be expected from the
Analog I/O HART module?
When the Analog
I/O HART module connects for the first time, the module polls the
device to determine the address. There are 16 possible
addresses so there may be a delay before instrument communication
begins. Once the address is found the address is reassigned to
zero and the HART dialog may begin. Reassigning the address helps
to minimize the startup delay. Disabling HART on unused
channels will also reduce start-up time. Once the startup dialog
is complete the module begins polling for data. Data acquisition
time varies depending on the number of active HART
channels. Typical data updates occur at a six second interval with
all channels enabled for HART.
