Biamp LSI-16e - Manual (Page 13)

13
SECTION HEAD
LSI-16/LSI-16e REAR PANEL
Connections and Input Types
External Connections
Both Chassis Ground ( ) and Isolated Ground ( ) are available on the IM-16 connectors.
By default, all input circuits are isolated with respect to the LSI-16 ground. Any external input connections must be logic referenced to the Isolated
Ground. This configuration allows external equipment to be interconnected to the LSI-16 without ground current interaction between devices.
The IM-16 ground appears on a single terminal (Pin 1) on each of the two connector banks (‘Option A’ and ‘Option B’). This should only be used if
circuit isolation is not required and should only be connected to the cable screen.
The two issolated grounds of the IM-16 board are connected internally. For ease of wiring each connector, every Control Input pair has an Isolated
Ground connection adjacent to it.
Types of Input Circuit
The logic level of each input on the IM-16 may be independently determined in the Vocia software to operate one of three ways. These are;
• TTL: 2V to 5V logic sense. To enable a TTL input, apply a TTL logic high with respect to Isolated Ground. This can be configured in software
to detect a low to high or high to low transition.
• High Range: To enable a High Range input, use a dry contact to switch the input to a voltage of 24V DC with respect to Isolated Ground.
This can be configured in software to detect a low to high or high to low transition.
• High Range – Monitored: This circuit is implemented in the same way as the ‘High Range’ input. This option allows monitoring of each input
for short to ground and open circuit. In order to sense open circuit, a terminating resistor must be fitted between each Control
Input and Isolated Ground at the far end of the input circuit being sensed. The IM-16 will sense open circuits on the line between its input and
the terminating resistor. Shorts to Isolated Ground are sensed across the entire line being monitored. A 6k8Ω resistor should be used for each
input. If a monitoring fault is detected on any input the logic state or transitions on that input will be ignored until the fault is cleared. High
Range – Monitored inputs require a low to high transition to enable the input (transition direction not configurable).
System Fault Relay Connection
This relay is activated when the LSI-16/LSI-16e is fully operational. It may be used for informing external devices about the LSI-16/LSI-16e’s
operating conditions or sounding an alarm that indicates the LSI-16/LSI-16e is not functioning reliably.
RS232
The RS232 port can be used to send VTP commands to the LSI-16/LSI-16e and monitor Vocia system health. Please see Help Files for details.
24V DC Connector and LED
This is the primary (main) power supply input for the LSI-16 and as such must be fed from a suitable source of 24V DC capable of 15 watts (625mA).
The 24V DC supply has to be sourced separately. In typical installations, this supply will be provided from a power supply compliant with local
norms and required standards (typically battery-backed). The adjacent LED indicates the presence of power.
Sourcing 24V DC for High Range Inputs
The High Range logic inputs should be driven from a contact closure (relay or switch) in connected equipment. The High Range inputs expect to
sense a transition from low-state voltage (0-11V) to high-state voltage (12-30V). A 24V Logic High Reference output voltage is provided by the IM-16
for this purpose. Alternatively an external 24V reference may be used. If an external supply is used, the ground connection of the external supply
must be wired to the IM-16 Isolated Ground.
IP30 Compliance
The LSI-16 is designed for ingress protection to the IP30 standard. In order to maintain this compliance, any unused terminal connectors on the back
of the unit must be fitted with the supplied terminal blocks.