The Flex Terminal Unit FTU is a self-contained processor-controlled data gathering unit, operating from a -21 to -60 v DC station battery. It is capable of monitoring up to 32 alarm points and accepting up to 32 analog voltage inputs or controlling up to 16 remote control points. The alarm point inputs may be activated by dry contacts, open collector transistor keying to ground or wet contacts with positive or negative voltage.

The FTU can output negative or positive voltage to be keyed by PNP or NPN transistor to ground. The polarity selection is by means of soft-straps within the FTU and selection is ganged in banks of 8 points. Therefore, an FTU with 32 alarms may have 24 points operated with negative and 8 points operated with positive polarity inputs or any combination of 8 points.

All information contained within the FTU is maintained in a combination of RAM and Flash memory and may be accessed by a Local Access Port (LAP) program for graphical viewing. Password protected configuration editing or operation of relays from the LAP is permitted while the MCTU is polling the FTU. System activity is summarized by three rear panel LED lamps. A Major and Minor alarm condition is indicated by a Red and a Yellow LED lamp respectively. Power ON but loss of communications is indicated by steady ON Green LED lamp. Communication with the Master is indicated by the ON Green LED lamp blinking off briefly. Flex Terminal Program 2 (FTP2) allows local operation of remote control functions, viewing and editing configuration of alarms and control points. Detailed configuration information, including point labels, is displayed and modified on configuration pages. System Date and Time clock may also be viewed on the bottom portion of the FTP2 summary page.

RS-232 (V.28) or RS-422 (V.11) electrical interface at 1200 bps, (can be set from 1.2 to 9.6 kbps, in standard bit?rates) with De-jittering and built-in 2-port digital bridge. Ports 1 and 2 of the bridge are guarded with a relay operating in the fail-safe mode to bypass the station in case of total failure. Also, the FTU is capable of 19.2 kbps asynchronous communications, however, in case of equipment failure, although the protection relay will have back-to-back connected the data channel, the data signal cannot be repeated due to the unavailability of the de-jittering circuit in the FTU, unless the data channel in use has de-jittering built-in.

Optional built-in PCMCIA Telephone Dial-up modem for direct access via the PSTN at times of communication failure or when a data channel is unavailable and the FTU must use the telephone lines to communicate with the MCTU.

If operation over the baseband of analog radio or VF channel multiplex equipment is required, a Network Communications Bridge Analog (NCBA) with a 1200 bps ASK Modem must be used to convert the RS-232 (V28) data signals to ASK Tones and VF bridged to the analog channel. The FTU operates with its own monitoring program, independent of the Master Terminal. It continues to Date and Time stamp and logs information in RAM. Once 4096 line items have been reached, new events are appended to and an equal number of oldest line items are discarded from the log. When called by the MCTU, these buffered events and logs are transmitted to the Master. The FTU will continue logging information even if the MCTU is shut-down for long periods of time. Multiple events on any one or more points are held in the 4096 event history buffer until the Master is back on-line and polls the FTU. When called, the FTU transmits buffered events with their original Date/Time information to the Master. System history and sequence of events information are not lost due to Master Terminal shut-down/failure or Microwave outage.