Cordex® 24-400W 19” Integrated Shelf Installation and Operations Guide | 6 - Wiring and Connections
Current input #1 is wired internally to the system current shunt for shelves with integrated distribution, and
wired to an external shunt for bulk distribution shelves.
Temperature Sensor
Temperature Probe input channels provide connections for up to two temperature sensors. A voltage is
supplied to these terminals for sensor measurements. Temperature sensors are available from Alpha in
various lengths.
Digital Inputs
The digital input channels are used to monitor various alarm and control signals. All input channels are
voltage activated and accept a bipolar (i.e. negative or positive) DC signal directly.
For shelf modules with integrated distribution, D1 is wired internally for CB/fuse trip. D2 is available for
customer connections as required.
Connection Method
Typical Alpha systems use the “reset with Hot and trigger with Ground” connection. The digital input is
wired in such a way that the Hot is wired directly into one of the input terminals:
•
positive input for +12V and +24V systems
•
negative input for -48V systems
The other input terminal is wired to the Ground (common) of the system through a relay (dry contact –
usually located on the equipment requiring monitoring). This method allows the digital input to receive (or
not receive) a Ground signal on an alarm.
Figure 10.
Digital Input Connection Method
VE Ground
Hot
Hot
VE Hot
Relay from
Equipment
VE Hot
VE Ground
Relay from
Equipment
Digital Input 12V and 24V
Systems
Digital Input 48V
Systems
Programming the Digital Input
The digital input channels can be programmed for “active high” or “active low. Active high indicates,
“alarm on the presence of a ground signal” and active low indicates, “alarm on the removal of a ground
signal.” See controller software manual for detailed instruction on programming.
9400021-J0 Rev B
Page 29