Abus Terxon MX Installation Instructions Manual page 30

UK
If you use the siren, transistor output OP1 (programming
menu: menu item 081) must be set to "Bell" (00).
Use the resistors provided to connect the SG1900
(1kOhm). Do not forget to change the connector of the
internal battery from NC to Battery (–).
Se also the operating instructions of the signalling
equipment, which you should read carefully.
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