User Manual

Chapter 4: Module Data, Status, and Configuration
U ser 's M a n u a l 0 300 21 5- 03 R ev. A
6-3
Input Data No t Valid Conditio n
The general status bits S0 to S3 also indicate whether or not the input da ta for a particular
channel, 0 through 3, is being properly converted (valid) by the module. This “invalid
data” condition can occur (bit set) when the download of a new configuration to a
channel is accepted by the module (proper configuration) but before the A/D converter
can provide valid (properly configured) data to the 1769 bus master/controller. The
following information highlights the bit o peration of the Data Not Valid condition.
1. The default and module power-up bit condition is reset (0).
2. The bit condition is set (1 ) when a new configuration is rece ived and d e termined
valid by the module. The set (1) bit co ndition remains until the module begins
converting analog data for the previously accepted new configuration. When
conversion begins, the bit co ndition is reset (0). The amount of time it takes for the
module to begin the conversion process depends on the number of channels being
configured and the amount of configuration data downloaded by the controller.
NOTE: If the new configuration is invalid, the bit function rem ains reset (0) and the
module posts a configuration error. See Configuration Errors on page 9-4.
3. If A/D hardware errors prevent the conversion process from taking place, the bit
condition is set (1).
6.3.4 Out of Service Status Bits OS0 to OS3 (Word 5)
Bits SO0 through SO3 of word 0 indicate whether the associated channel is out of service
(i.e. automatic HART acquisition is suspended).
Note: A channel that is p laced out-of-service (i.e. Suspended) will a utomatically
resume service after three minutes, as long as no pass-through co mmands are issued
before the three minutes expires.
6.3.5 Over-Range Flag Bits O0 to O3 (Word 6)
Over-range bits for channels 0 through 3 are contained in word 6, even-numbered bits.
They apply to all input types. When set (1), the over-range flag bit indicates an input
signal that is at the maximum of its normal operating range for the represented channel or
sensor. T he module automatically resets (0) the bit when the data value falls below the
maximu m for tha t ra nge.
Note: If a channel is configured f or a voltage typ e input and an open- circuit condition
is present, the over-range flag b it will be set to indicate the op e n circuit condition and
the associated channel data word will display the full-scale value.
6.3.6 Under-Range Flag Bits U0 to U3 (Word 6)
Under-range bits for channels 0 through 3 are contained in word 6, odd-numbered bits.
They apply to all input types. When set (1), the under-range fla g bit indicates an input
signal that is at the minimum of its normal operating range for the represented channel or
sensor. T he module automatically resets (0) the bit when the under-range conditio n is
cleared and the data value is within the normal operating range.
Note: If a channel is configured for a current type input and an o pen-circuit cond ition
is present, the under-ra ng e flag bit will be set to indicate the o pen circuit condition and
the associated channel data word will display the minimum scale value.
6.3.7 High Process Alarm Flag Bits H0 to H3 (Word 6)
The high process alarm flag is set when the measured analog signal exceeds the high
process alarm setpoint. The high process alarm setpoint is defined in Section 6.4 Module
Configuration.