14 Pelco Manual C681M-D (2/02)
REC
ALARM-OUT
POWER OFF
POWER ON
MODE-OUT
CALL OUT GND
CALL OUT
DC 5V OUT
MAX 30mA
CLOCK ADJUST
REC
POWER ON
POWER OFF
ALARM OUT
MODE OUT
CALL OUT
CALL OUT GND
First Unit Second Unit
GND
GND
GND
GND
GND
<Interface circuit inside the unit>
5V
5V
10kΩ
22kΩ
Input
terminal
0.047µF
GND
POWER ON/POWER OFF/
ALARM IN/REC/CLOCK ADJ
Input terminal 
• Input Circuit
<Interface circuit inside the unit>
Output terminal
GND terminal
ALARM OUT/MODE OUT Output terminal 
• Output Circuit
<Interface circuit inside the unit>
CALL OUT terminal
CALL OUT GND terminal
CALL OUT output terminal 
• Output Circuit
The REC input terminal is used to start recording. Refer to
Series Recording
in this step for
more information. The input is active when a ground or low voltage signal is applied. The in-
put is non-active when the terminal is open.
The MODE OUT output terminal is used to indicate the status of the recorder (refer to
Mode
Out
in the
Programming
section for more information). It can also be used to turn on an-
other recorder (refer to
Series Recording
in this step for more information). The output is
active when the terminal is at a low voltage level and non-active when the terminal is open.
Maximum current drive is 7 mA DC, and the maximum voltage is +24 VDC.
The CALL OUT output terminal is used for warnings (refer to the
Warnings
section for more
information). It can also be used to turn on another recorder (refer to
Series Recording
in
this step for more information). The output is active when the optical coupler is turned on
and non-active when the optical coupler is turned off. Maximum current drive is 7 mA DC,
and the maximum voltage is +24 VDC.
Figure 10. Schematics for Input and Output Terminals
SERIES RECORDING
By connecting multiple units in series as shown in Figure 11, when the one unit’s hard disk
is full, the next unit automatically begins recording.
In this example, when the first unit’s hard disk is full, the second unit begins recording;
when the second unit’s hard disk is full, the first unit begins overwriting its hard disk. If you
do not want the first unit to overwrite its hard disk, do not connect MODE OUT from the
second unit to REC of the first unit. The series recording function can also be activated by
connecting the CALL OUT terminal in place of the MODE OUT terminal; the disk storage
capacity setting is made in the Call Out menu. When the CALL OUT terminal is used, if the
first unit reaches the preset capacity, experiences a malfunction, or otherwise cannot con-
tinue recording, the second unit begins recording.
Figure 11. Connecting Recorders in Series