Analog Output Quality - ABB Command Series Instruction Manual

A test quality block (function code 31) can be configured to transfer
the associated operator manual/auto station to manual, shut down
the process or send a warning to an annunciator (Fig. 4-2).
NOTE: Configuration of a test quality block requires the use of a
Type CTT Configuration and Tuning Terminal or other software con-
figuration tool.
Only process I/O, module bus inputs, and Plant Loop inputs can be
tested for quality. Quality is not propagated through the controller
function blocks. All internal points will have good quality.

ANALOG OUTPUT QUALITY

A broken analog output current loop may or may not cause the con-
troller to go into the bypass operation depending on how it is config-
ured. A test quality block (function code 31) can monitor analog
output quality. When the current loop is broken, a bad quality is regis-
tered (Fig. 4-3).
Specification S18 within function code 80 is the transfer to manual
mode input. If S18 is set to the block address of the test quality block
associated with the analog output, the controller will transfer into
manual control mode.
Depending on the application, it may be desirable to configure a trip
block (function code 32), which would place the controller into bypass
mode (registers as ERROR mode on the Type CTT terminal) if a
break in the analog output current loop is detected (Fig. 4-3). If, and
only if, a trip block is activated, will the controller go into bypass oper-
ation when the analog output current is broken. Specification S1 of
the trip block is the block address of the test quality block associated
with the analog output. Note that all configured control loops are
placed in bypass mode when a trip is activated.
CONFIGURATION
D.O. LOCK
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