Siemens TC12 Installation, Commissioning And Maintenance Handbook page 171

Switch operation:
Word Selector
If this switch is set to 1 word, only the 37 way plug (OTU mode) or 37 way socket
(controller mode) can be attached. Only the first eight data switches then operate.
Generally this switch should be left in the 2 word position. Both the 37 way
and 25 way plug (OTU mode) or 37 and 25 way socket (controller mode) must be
connected up. All 16 data switches then function.
Mode Switch
Selects mode; OTU/OFF/CONTROLLER
Lamp Test
Checks all LEDs are working
Data Switches
Controller Mode
OTU Mode
Transmission Confirm
For use in OTU Mode only, to confirm valid control message to MCE 0105
specifications.
5.2.1.3 Indicators
The following LED (Light Emitting Diode) indicators are provided:
A transmission confirm indicator active in the controller mode only.
A connection fault indicator which is lit if a mode is selected without the correct test
led connections, or conversely, if the correct test lead connections are made but
the mode selection is incorrect.
16 data bit indicators for the two 8-bit words operating as follows:
CONTROLLER MODE
OTU MODE
5.2.1.4 Connection Check Logic
The connection Check Logic circuit is incorporated within the OTS to ensure that:
- The correct test cable is used and is fully inserted into the D connectors.
- The word switch is selected appropriately to correspond with the requirements of
the OTU/Controller.
- The mode switch is set to the respective simulation mode.
666/HE/43100/000
TC12 Installation, Commissioning & Maintenance Handbook
: Switch down = set reply bit (e.g. confirm stage)
: Switch down = set control bit (e.g. force stage)
LED ON = set reply bit (e.g. force stage)
LED ON = set control bit (e.g. confirm stage)
Page 161 Issue 10