APPLICATION NOTE #104 CT2525/6/7 Series CT7005/6 Series OPTIONAL

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APPLICATION NOTE #104 CT2525/6/7 Series CT7005/6 Series OPTIONAL

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CIRCUIT TECHNOLOGY
APPLICATION NOTE #104
CT2525/6/7 Series CT7005/6 Series OPTIONAL CONTROL SUBSYSTEM FLAG TERMINAL FLAG BITS
Point Contact: John Vanchieri Tel:(516) 752-2484
APPLICATION NOTE #104
Revised 6/96
more powerful aspects CT252X series BC\RT devices ability control certain bits Status registers conditions overall system. conditions that cause Subsystem Flag (SSF) Terminal Flag (TF) bits Status Word reset controlled subsystem using ENABLE, DECODE, NEXTSTATUS, STATUS UPDATE inputs.
DEFAULT CONDITIONS
ENABLE inactive (high) then other three option lines disabled. Terminal Flag Subsystem Flag behavior will same described MILSTD-1553B document, which states: 4.3.3.5.3.9 Subsystem flag bit. status word time shall reserved subsystem flag bit. This bit, when used, shall flag subsystem fault condition, alert controller potentially invalid data. Multiple subsystems, interfaced single which individually require subsystem flag signal shall logically their individual signals into single status word bit. event this logical performed, then designer must make provisions separate data word identify reporting subsystem. logic shall indicate presence flag, logic zero absence. used, this shall logic zero. 4.3.3.5.3.11 Terminal flag bit. status word time shall reserved terminal flag function. this optional. This bit, when used, shall flag fault condition. logic shall indicate presence flag, logic zero, absence. used, this shall logic zero.
CT252X design allows control both software, through Operation register, hardware, through SSER input (CT252X10 only). will register fault condition either Operation register programmed SSER line from subsystem low. status will then fault condition exists when valid command received with exceptions specified 1553B (i.e. Transmit Status Word Transmit Last Command Word). reset either power-up initialization reception Reset mode command. CT252X design allows status either detects fault transmissions (continues background self-testing), timeout fault occurs ("babbling terminal" syndrome), loss proper address parity, Initiate Selftest mode command timeout check fails. these faults will condition, which only cleared powerup initialization Reset mode command, fault condition longer exists. fault condition been set, then Status will upon reception valid command word, with exceptions specified 1553B.
TIMES
Sync
Remote Terminal Address
12-14 Message Error Instrumentation Service Request Broadcast Command Received Busy Subsystem Flag Dynamic Control Accept. Terminal Flag Parity Reserved
Figure MIL-STD-1553B Status Word Format
APPLICATION NOTE #104
Revised 6/96
OPTIONAL CONTROL
ENABLE held low, then three options described below available essentially independent. Any, all, none selected.
and/or Status word. Note that this behavior meet "letterof-the spec" described MIL-STD1553B, considered "preferred" behavior some users.
RESETTING RECEIPT VALID COMMANDS
ENABLE selected other three option lines held high, then Status Word bits will reset receipt valid command with exception Transmit Status Transmit Last Command. Note that this mode, will never seen Status Word, will only seen SSERR latched low. Also note that will seen response Transmit Status Transmit Last Command preceding Status Word clear, regardless actions taken SSERR line after clear status transmission.
REPORTING NEXT STATUS WORD AFTER FAULT
NEXT STATUS selected (held low), then will appear response very next valid command after fault except Transmit Status Transmit Last Command. flag(s) will reset receipt valid command following status transmission with flag(s) except Transmit Status, Transmit Last Command, noted following section "Preserving Word".
PRESERVING WORD (when using ENABLE option)
order preserve Transmitter Timeout Flag, Internal Handshake Failure, Word Count High, Word Count Low, Loop Test Failure Bits Word, necessary select DECODE (hold low). This will prevent resetting those bits Transmit Word mode command immediately follows fault follows Transmit Last Command Transmit Status immediately following fault. will also prevent resetting Bits Status Word. other valid commands will cause those Word bits Status Word bits reset.
STATUS REGISTER UPDATE FAULT OCCURRENCE
STATUS UPDATE selected (held low), then will appear response Transmit Status Transmit Last Command issued first command after fault occurs. other command (except noted Preserving Word section) will reset fault condition(s) longer exists. Repeated Transmit Status Transmit Last Command immediately following fault will continue show
SUMMARY
This paper attempted answer most commonly asked questions concerning CT252X series hybrids. Forthcoming application notes will address additional hardware concerns software methodology. Information CT252X series, other 1553 data product, obtained calling Applications Dept. (516) 752-2484.
information presented herein best knowledge true accurate. warranty expressed implied made regarding capacity, performance suitability product. strongly urged ensure that information given been superseded. APPLICATION NOTE #104
Revised 6/96

APPLICATION NOTE #104 CT2525/6/7 Series CT7005/6 Series OPTIONAL

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