Monroe Electronics R174A - Manual (Page 7)

7
OPERATION
The 2 x 1 relay sets may be switched three ways: By using a DTMF signal programmed into the
included decoder for each switch assembly. By means of the contact-closure inputs on the
control screw terminal. Or, by using Switchware

software on a PC, through an RS-485 circuit.
Switching priority is from contact closure first, RS-485 second, and DTMF third. This means
that if the contact closure is used, the switch may be turned on or off no matter what the other
controls do. If the RS-485 is used, it supercedes DTMF on or off commands.
When the unit receives a DTMF control sequence a 250 mS pulse is output as closure from
SWTICH to GROUND (refer to drawing below). This allows activation of a VTR or other device
as desired.
Switching time is <30 mS.
G
RO
UN
D
G
RO
UN
D
AU
D
IO
IN
SW
ITC
H
GROUND
GROUND
AUDIO IN
SWITCH