Dry Contact Operation

The transmitter will detect a contact closure on the provided connector. Only normally open operation is supported. Typically the contact is a switch or relay. The input cannot be driven by any voltage source, a pull-up resistor is provided in the transmitter. The TX-74USB has 2 Dry Contacts available for inputs.

Turn Off Dry Contact Paging

To turn off dry contact paging, send the command SINP,0.

A contact closure still respond with the following message on the serial port CONTACT1 DETECT.

Turn On Dry Contact Paging

To turn on dry contact paging, send the command SINP,1,PGR,MSG, where PGR is the pager number to page and MSG is the alphanumeric message to be sent.
##On TX-74USB

• To turn on Contact 0, send the commands SINP,1,PGR,MSG or SINP0,1,PGR,MSG.
• To turn on Contact 1, send the commands SINP1,1,PGR,MSG.

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Note

• Only alphanumeric pagers are supported.
• The System ID used is the default value in the transmitter, which is set with the RID,nn command.

Dry Contact Example

Command

C

SINP,1,34,Fire alarm test

A contact closure will respond with the following message on the serial port (pager set to 34, system ID set to 2)

C

“CONTACT1 DETECT” “PAGED Num:34 SysID:2”
SINP1,1,55,Door Open