User Manual

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Siemens TX-I/O Engineering and installation guide CM110562en_13
Building Technologies Display, operation, and diagnostics 2019-05-15
9.3 Local override
• The local override facility is 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
automation station 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.
• Local override may be disabled in the configuration
• All safety-relevant functions must be implemented with external solutions.
• The local override must not be used for safety shutdown operations.
• 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 lies with the operator. 
9.3.1 Override button
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.
9.3.2 Override status LED
The yellow "Override" LED indicates for each I/O point that local override is active:
Description
LED (yellow)
Normal (automatic operation)
OFF
Local override active
ON
multi-stage function
• The LEDs of all the associated I/O points are ON.
• The function can be overridden on any I/O point.
Reminders, errors
See below under "Diagnostics".
9.3.3 Priority
Local override has first priority, followed by tool override via TX-I/O Tool, and function
test via BIM Tool, and (lastly) automatic mode via process value / backup value.
Warning