LMD222 and LMD224 Series
Operations Manual
Eberle Design Inc.
Page 5
2.2.4 MINIMUM PRESENCE TIME
When the diode (1N4148WS) labeled OPT4 is installed, the LMD Series will limit the
minimum presence time to 100 milliseconds.
2.2.5 PULSE MODE (P)
The Pulse mode will provide a 125 ms ± 25ms width output pulse for each vehicle entering
the loop.
2.2.6 CALL MODE (C)
The Call mode will set the channel output to the Call state (True). This mode can be used
to provide a continuous Call state to the Controller Unit regardless of the state of the
detection zone. Loop fault conditions are ignored in this mode.
2.2.7 OFF MODE (-)
The Off mode will set the channel output to the No Call state (False). This mode can be
used if the channel is not used or not connected to a loop. Loop fault conditions are ignored
in this mode.
2.3 SET THE FREQUENCY
Pressing the FREQ button once will display the Frequency
Level (1 – 4) without changing the setting. After pressing
the FREQ button to display the current Frequency Level,
the setting can then be changed by pressing the FREQ
button again. The display will automatically return to the
normal display after several seconds.
The Frequency level needs to be changed only if
interference occurs between adjacent loops connected to different sensor units.
Interference or crosstalk may manifest itself as chattering of the call output or a detect call
occurring at the same time as an adjacent unit when there is no vehicle present. If crosstalk
is suspected, try to separate the frequencies of the channels causing the problem. A
minimum of 5 KHz separation is recommended. Four frequency levels are available on
each channel to assist in alleviating interference affecting more than two units.
Changing the Frequency Level will cause the channel to retune.
2.3.1 DISPLAYING THE LOOP FREQUENCY
The current loop frequency is displayed by after pressing the FREQ button to display the
current Frequency Level. The frequency is shown in KHz with a “-“ symbol displayed both
before and after the numeric digits shown on the DEFLECTOMETER
®
.
For example, after pressing the FREQ button once the display sequence might show:
“3”
“-“
“2”
“7”
“-“
This sequence would indicate Frequency Level “3” and a loop reference frequency of 27
KHz.
2.4 MISCELLANEOUS
2.4.1 CHANNEL OFF
If a channel is not to be used, it may be switched off (disabled) by setting the Operational
Mode to OFF. See section 2.2.6.
Frequency
Level 4
High
Level 3
Medium High
Level 2
Medium Low
Level 1
Low
