Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
RFL VF-6I RFL Electronics Inc.
December 15, 2011 18 (973)
334-3100
FUNCTIONAL DESCRIPTION
SYSTEM OVERVIEW
The VF-6I is a 4-wire Orderwire Voice Frequency Channel Module designed for RFL IMUX 2000 T1
and E1 multiplexers. It is designed as a direct replacement for the RFL VF-6 and can communicate
with the RFL VF-5A. The VF-6I can interconnect multiple locations (nodes) for applications
involving voice or multiple voice grade modems for alarm and control applications.
In a bridge configuration, each mode hears the master node, and the addressed node responds back to
the master. However, all nodes other than the master do not hear the response. In a multi-drop
configuration, every node hears every other node, since there is no master.
One of four Transmit Modes can be selected: Continuous, Voice Activate (VOX), Hook-Switch, and
Receive Only. In Continuous Mode the local audio signal is added to the transmit data stream
regardless of signal level or any control input. In Voice Activate Mode (VOX) the local audio signal is
added to the transmit data stream if the threshold set by the threshold level switches, VOX0 and
VOX1, is exceeded. In Hook Switch Mode the local audio signal is only added to the transmit data
stream when the hook-switch control input is externally grounded. In Receive Only Mode the local
audio signal is never added to the transmit data stream regardless of the signal level or any control
input. Data is only received.
The VF-6I accepts a single voice channel as input and uses μ-law PCM encoding to convert the analog
voice into an 8-bit, 64-Kbps digital signal. The VF-6I can be configured via local switches (SW1 thru
SW5) or remotely with the RFL SCL (Simple Command Language). However, the attenuator settings
can only be set with the physical switches (SW4 & SW5).
Channel-Associated Signaling (CAS) is used in E1 applications, while Robbed-Bit Signaling (RBS) is
used in T1 applications. Signaling can be disabled in T1 and E1.
Refer to the VF-6I Simplified Block Diagram shown in Figure 11.
BACKPLANE AND POWER CONNECTIONS
The VF-6I occupies a single physical slot in the multiplexer and conforms to the RFL IMUX 2000
backplane signal format. All T1 and E1 backplane signals in and out of the VF-6I are driven with
74HCT125 drivers except for the SCB clock, sync and data signals. All control signals passing
through the backplane from the I/O module are pulled up to +5V through 4.7 K Ohm resistors.
The VF-6I requires +5V, +15V, -15V, -48V, and ground which are supplied by the IMUX 2000
backplane. The +5 volt input includes an inductor which lowers the inrush current to prevent
interruption to the power during module insertion. TP2 is the +5V testpoint. TP3 is the ground
testpoint. All pins which connect to the backplane except for voltages and grounds are cut back to
prevent components from being driven by signals before the module is fully powered.
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