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40 Configuration, Startup and Operation
S
ection 3: Configuration, Startup and Operation 6888Xi Advanced Electronics Instruction Manual
December 2012 PN 51-6888Xi
actual process value.
• Purge End Premature – This indicates that the configured Purge Time expired prior to
the diagnostic algorithm determining that the sensing cell is completely returned to the
process reading. This would occur primarily with the Rate mode algorithm.
• Fail Reach Process – This indicates that the configured Purge Time expired prior to the
diagnostic algorithm reaching the process reading that was indicated at the start of the
calibration. This would occur primarily with the Proximity mode algorithm.
• Diffuser Plugging – This warning is generated when Purge Time % has reached 75%
indicating a near term risk that the configured purge time could expire before the
process value is reached after a calibration purge.
• Constant Shifting – This indicates that the calibration constant is trending negative
over an extended period of time which could also indicate that calibration test gas is
causing excessive pressurization of the sensing cell during the calibration.
3.4 System Parameter Descriptions
Among the parameters available through the 6888Xi and 375/475 Field Communicator menus
are a number of "System Parameters". The system parameters define variables that configure the
6888Xi in the transmitter system. System parameters are described in Table 3-4.
3.5 Probe Parameter Descriptions
Among the parameters available through the 6888Xi and 375/475 Field Communicator menus
are a number of "Probe Parameters". The probe parameters define variables that configure a spe-
cific probe in the transmitter system. Probe parameters are described in Table 3-5.
3.6 Operation Via HART/AMS
The 375/475 Field Communicator is a handheld communications interface device. It provides a
common communications link to all microprocesor-based instruments that are HART compati-
ble. The handheld communicator contains a liquid crystal display (LCD) and 21 keys. A pocket-
sized manual, included with the 375/475 Field Communicator, details the specific functions of
all the keys.
The 375/475 Field Communicator accomplishes its task using a frequency shift keying (FSK)
technique. With the use of FSK, high-frequency digital communication signals are superimposed
on the 6888Xi's 4-20 mA current loop. The 375/475 Field Communicator does not disturb the 4-
20 mA signal, since no net energy is added to the loop.
NOTE
The 375 Field Communicator must be upgraded to System Software 2.0 with Graphic License for opera-
tion with the 6888Xi. The AMS software must be upgraded to AMS 8.0 or above for operation with the
6888Xi.
Contact Emerson Process Management’s Global Service Center (GSC) at 1-800-833-8314 to upgrade
the 375 Field Communicator software to System Software 2.0 with Graphic License.