Emerson E2 Manuel D’Utilisation

For point log groups, regardless of the resolution, the 

following applies when errors occur in log data:

NO 

DATA 

(LOG_DATA_-

NONE)   

Actual data value of the 
output is NO_VALUE 
but output status is not 
CELL_OUT_FAIL or 
CELL_OUT_INACT

PT FAIL (LOG_PT_FAIL)  

Data is NO_VALUE 
and status of output is 
CELL_OUT_FAIL -- 
could occur when point 
cell has passed one min-
ute update  

PT 

INACT 

(LOG_PT_DIS-

ABLED)  

Status of output is 
CELL_OUT_INACT 
and this appears regard-
less of the value of the 
data – this may occur at 
startup                 

ERROR

Indicates log error type 
could not be determined 
but the LOG_ERROR_-
FLAG was set in the 
data (this is display only 
and might indicate cor-
rupted data)  

A displayed value of DATA N/A (LOG_DATA_NA) is 

used in medium and low resolution logs when that particu-
lar type of data cannot be logged in that resolution. Pulse, 
one shot, and system list types cannot be logged in 
medium and low resolution log groups. 

Because the user may need to log more data than the 

default logging of the E2 can hold in memory, the user can 
set the resolution type in the log manager to determine 
how the desired points will be logged. E2 converts these 
analog sample values to this lower resolution (Low or 
Medium) by:

• Adding/subtracting an offset

• Multiplying by a scaling factor

• Rounding to the nearest integer value of the size 

appropriate for the desired resolution

Clipping occurs whenever the conversion process 

results in a sample value that falls outside the range of the 
selected log resolution. For example, converting a value of 
750 PSI to low resolution would result in a compressed 
sample value of 609 PSI (refer to Appendix E: Com-
pressed Point Log Sample Limits and Precision Tab). 
Low resolution only allows values up to 609 PSI; there-
fore, the sample is said to be “clipped.” If the value that 
will be logged is anticipated to exceed the high or low 
range for a particular log resolution, a higher resolution 
should be chosen.

High Clipping occurs when a compressed sample 

value is above the range allowed by the set resolution. In 
this case the sample value is considered “high-clipped” 
and the data recorded will be the high-clipped value and 
logged at the highest possible valid value. 

Low Clipping occurs when a compressed sample value 

is below the range allowed by the set resolution. In this 
case the sample value is considered “low-clipped” and the 
data recorded will be the low-clipped value and logged at 
the lowest possible valid value.

Points of certain data types cannot be compressed due 

to the nature of their data values. These points are called 
Incompressible Points. Refer to the following table for the 
data types that are considered to be incompressible at cer-
tain resolutions:

PULSE_TYPE

Low and Medium

ONE_SHOT_-
TYPE

Low and Medium

SYS_LIST_TYPE

Low and Medium

The Base Log group is a permanent logging group and 

cannot be deleted. When a new application is added to the 
system, the inputs and outputs that are logged by default 
are associated with the Base Log group.

Points are pre-configured to be logged for newly added 

applications. Many of the most important inputs and out-
puts within an application are already pre-configured to be 
logged, and all of these inputs belong to the Base Log 
Group. Simply define the inputs and outputs to enable log-
ging; no special set up is required. Logging is done auto-