Rockwell Automation 1797-IE8NF FLEX Ex 8 Input Analog, HART and Noise Filter Module - Manual (Page 28)

28 FLEX Ex 8 Input Analog, HART, and Noise Filter Analog Modules
Publication 1797-5.5 - September 2011
HART Read Back
(1797-IE8H) The HART Read Back bits show deviations between the analog
measured current value on a loop (by the 1797-IE8H) and the digital real
current (sensed by the HART device on its own) received by the
1797-IE8H during HART communication in the background. This
functionality can be turned on by defining a HART Readback Threshold
greater than 0. See
1797-IE8H CE, CENELEC I/O Entity Parameters on
page 42 . This functionality is used to recognize loop errors whereby a
parasitic current is bypassing the 1797-IE8H.
Range: 0 = normal, 1 = HART Readback threshold is exceeded.
HART Read Back
Threshold
(1797-IE8H) Delivers the percentage value (in steps of 1%) of the threshold for
forcing the HART read back indication (input signal deviation
HART/Analog) with a 31% maximum deviation.
If there is no HART transmitter on the loop or the loop is not in the
transmitter list, the function is switched off internally in the I/O module.
Range: 0 = disabled, 1…4 = not supported from I/O module (set to 5
internally), 5…31 = percentage threshold data (5…31%).
HART
Communication
(1797-IE8H) Range: 0 = normal, 1 = HART communication is currently occurring.
HART Transmitter
List (1797-IE8H) When this bit is set (1), it indicates that a HART field device was found
during the rebuild sequence on the associated channel.
Range: 0 = transmitter was not found, 1 = HART transmitter was found.
Square Root
Threshold
(1797-IE8H) This setting affects all channels using Data Format 2 or 6. It sets low,
end-of-scale percent value at which square roots start being reported.
Below this level 0% is reported. This compensates for asymptotic
values of the square-root function as the input approaches 0.
Range: 0 = disabled, 1 = 2%, 2 = 5%, 3 = 10%
Extended
Configuration
(1797-IE8H) Configuration additions are needed for HART communications in Series
A mode. An extended configuration area is provided. This Extended
Configuration table is configured by writing a CIO or MSG instruction
with the following:
Class = 0x7D
Instance = Product location on flexbus (Use 1 for the module
located next to the adapter.)
Attribute = 0x65
Service = Set Attribute Single (0x10)
See 1797-IE8H CE, CENELEC I/O Entity Parameters on page 42 .
Field Descriptions