Pressing the # key 3 times will turn all relays off.
If you wish to terminate a relay command before it is completed, press the * key.
POLLING THE RELAY STATUS
To find out, or "poll", the current state of any relay, push the * key three times followed by the
relay number. The DT-55 will respond with a single low-pitched tone ( booop ) if the relay is off, or
two short high-pitched tones ( beepbeep ) if the relay is on. Note that if the power has failed since
the DT-55 was last called, the state of the relays may be the same as previously set (see
"SETTING THE OTHER SWITCHES", above), but the state of the relays cannot be determined
by polling. In this case, instead of the normal tones, the DT-55 will give an error tone, a low-
pitched pulsating tone. Once another relay command is received, that relay's state will once again
be known and may be polled.
POLLING THE STATUS OF THE INPUTS
To determine the state of the 10 input circuits, press the * key followed by the channel number.
Assuming that external switches are connected to the input terminals, the status tone will be a
"booop" if the switch is ON, or the beepbeep if the switch is OFF. Note that "ON" would
correspond to a low logic level, since one side of the switch circuit is ground.
To find out if the status of any input has changed since the DT-55 was called last, press the * key
twice followed by the channel number. If the channel has changed at least once, the tone
(beepbeep) will be heard. If not, the tone (booop) will be heard.
POWER-FAIL STATUS
When the DT-55 answers a call, and before access is granted, a rapid series of alternating high
and low pitched tones will be heard if the power has failed since the last call was made. This is an
indication that the unit is not able to be polled for the relay status, and also that it is not known
whether any of the logic inputs have changed state since last polled.
LOCAL OPERATION
With the DT-55 connected to the phone line, you might wish to test the unit without calling it from
another phone line. If there is a phone connected to the same line as the DT-55, call any number,
preferably one that will be answered by someone who can put your call on hold while you test the
unit. Or, if you call your own number, you will receive a busy signal. Then hold the LOCAL button
down, on the DT-55, until the line is answered, as indicated by the LINE light. You can then
proceed to use the phone to test the functions of the DT-55, even though you will still hear the
busy signal in the background.
RESET BUTTON
If a power transient or some other unusual condition causes the DT-55 to lock up or otherwise
behave incorrectly, pushing the RESET button will completely clear the unit to its initial power-up
state.
