Local Override; Override Buttons - Siemens TX-I/O TXM1.8D Functions And Operation

Warning
Siemens
Building Technologies
2.3

Local override

The local override and LCD facilities are available only on certain modules.
In principle, plug-in I/O modules with and without a local LCD panel/operator controls
are compatible and interchangeable.
Only outputs can be overwritten. Any attempt to overwrite an input results in an
error indication.
Local override also operates without a bus master, provided that the DC 24 V module
supply is present and the address key is plugged in.
With a change from automatic mode to local override, the last state is retained.
The bus master resumes control when the system is switched back to Auto.
The bus master is notified of local overrides and the associated values, and they are
permanently saved in the module (in CFC this is visible as follows:
StaFlg = Overridden, PrVal = set value).
Local override can be disabled for each single I/O function,
• All safety-related functions must be implemented with external solutions
• The local override must not be used for safety switch-off
• In compliance with the standard (ISO 16 484-2, Section 3.110), the module
executes all local overrides directly, without safety precautions or interlocks.
Full responsibility for all operations lies with the operator.
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• For multistate outputs the outputs are locked electronically against each other.
2.3.1

Override buttons

Pressing an override button in the middle enables or disables the local override
(press until the override status LED changes to ON or OFF).
When local override is enabled:
• Pressing "+" increases an output value or activates the relay.
• Pressing "–" reduces an output value or disables the relay.
• Repeated or sustained pressure changes the value by several stages until the
function stops at the highest/lowest stage.
• The I/O status LED and LCD display change accordingly.
Pressing "+" or "–" when local override is disabled produces an "error" indication.
TX-I/O™ Module system – Functions and operation
Indicators and operator controls
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CM110561en_08
2018-10-25