59629475804QXC View Datasheet(PDF) - Aeroflex UTMC
Part Name
Description
Manufacturer
59629475804QXC Datasheet PDF : 177 Pages
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Opcode
1110
1111
Definition
Load Minor Frame Timer. This opcode instructs the SBC to load the minor frame timer (MFT)
with the value stored in the eighth location of the current command block. The timer will be loaded
after the previous MFT has decremented to zero. After the MFT timer is loaded with the new value,
the SBC will proceed to the next command block. No command processing takes place (i.e., no
1553).
Return to Branch. This opcode instructs the SBC to return to the command block address saved
during a Branch opcode. No command processing takes place (i.e., no 1553).
Note: For retries with interrupts enabled, all interrupts are logged after message processing is complete.
3.2.1.2 Condition Codes
Condition codes have been provided as a means for the SBC to perform certain functions based on the RT’s status word. In a RT-
RT transfer, the conditions apply to both of the status words. Each bit of the condition codes is defined below.
Bit
Number
7
6
5
4
3
2
1
Description
Message Error. This condition will be met if the SBC detects an error in the RT’s response, or if it detects
no response. (The SBC will wait 15 s in 1553B mode and 9 s in 1553A mode before declaring a RT no
response.) See section 5.0, Enhanced S MMIT Family Operation for additional information.
Status Word Response with the Message Error bit set (Bit time 9 in 1553A mode). This condition is met if
the SBC detects that the RT’s status word has the Message Error bit set.
Status Word Response with the Busy bit set (Bit time 16 in 1553A mode). This condition is met if the SBC
detects that the RT’s status word has the Busy bit set.
Status Word Response with the Terminal Flag bit set (Bit time 19 in 1553A mode). This condition is met
if the SBC detects that the RT’s status word has the Terminal Flag bit set.
Status Word Response with the Subsystem Fail bit set (Bit time 17 in 1553A mode). This condition is met
if the SBC detects that the RT’s status word has the Subsystem Fail bit set.
Status Word Response with the Instrumentation bit set (Bit time 10 in 1553A mode). This condition is met
if the SBC detects that the RT’s status word has the Instrumentation bit set.
Status Word Response with the Service Request bit set (Bit time 11 in 1553A mode). This condition is met
if the SBC detects that the RT’s status word has the Service Request bit set.
3.2.2 Command Words
The next two locations of the SBC Command Block are for 1553
command words. In most 1553 messages, only the first
command word needs to be initialized. However, in a RT-RT
transfer, the first command word is the Receive Command and
the second command word is the Transmit Command.
3.2.3 Data Pointer
The fourth location in the SBC Command Block is the data
pointer that points to the first memory location to store or fetch
the data words associated with the message for that command
block. This data structure allows the SBC to store or fetch the
exact specified number of data words, thus saving memory
space and providing efficient space allocation. (Note: In a RT-
RT transfer, the SBC uses the data pointer as the location in
memory to store the transmitted data in the transfer.)
One common application for the data pointer occurs when the
SBC needs to send the same data words to several RTs. Here,
each Command Block associated with those messages would
contain the same data pointer value, and, therefore, fetch and
transmit the same data. Note that the Data Pointer is never
updated (i.e., the SBC reads and writes the pointer but never
changes its value).
S MMIT FAMILY
45
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