Interface
card Rev 3 FAQ v3.4
R. Sidwell
Dec 13, 2000
No. produced: 165
Start date of production: 11/2000
Serial number range: 18-182.
1553
Readback:
Monitoring of SVX currents,
temperature probe is done a 1553 interface and multiplexed serial ADC. Each
interface module 1553 Remote Terminal (RT) address depends on the position in
its crate; there are eight sub-addresses for the 8 channels on the board. The
address structure is shown in the table below. Note that each RT address spans
two slots in order to conserve 1553 masters.
|
Crate physical slot (from left when facing crate). J2, J3 index. |
RT address |
Sub-address range |
Connector range |
|
1 |
Not used |
|
|
|
2 |
20 |
1-8 |
1A to 4B |
|
3 |
20 |
17-24 |
“ |
|
4 |
21 |
1-8 |
“ |
|
5 |
21 |
17-24 |
“ |
|
6 |
22 |
1-8 |
“ |
|
… |
|
|
|
|
21 |
29 |
17-24 |
“ |
The 1553 interface to the
interface cards is used to extract voltage levels and state of health monitoring
information. The bus controller will
send a command word with the RT address for the card desired (starting at
address 0), the sub-address for the channel on the card desired (starting at channel 1), setting the
transmit bit to 1, and specifying 9 words to be transmitted. An illegal command
(e.g. asking for 1 word) returns the status word. Only the lower byte of each
16-bit word is used.
The
interface card upon receipt of this command will initiate the return of a
status word. Simultaneously an 8 bit analog to digital converter and
multiplexer will begin reading the voltage of the first data word. The analog to digital converter operates in
unipolar mode since voltages are always positive pending transmission. The
first conversion will be completed by the end of the transmission of the status
word.
When the
status word is completed the first data word transmission will be initiated and
the next voltage conversion will take place.
This will continue until the ninth data word.
???? Still valid?????A 10 second
timeout is being added to the 1553 interface, since the first message seen on
the bus after an idle bus of more than 10 seconds will be read
incorrectly. A broadcast wake up
message needs to be sent after the bus has been idle for more than 10
seconds. The broadcast message FBE7h be
used, however, the actual message is immaterial because the 1553 hardware will
not be able to actually read the first message after shutdown.
The 1553 readout order:
1) 1553 status word, high order byte. Normal=B8
2) Interface card serial number (0-255),
3) HDI state-of-health (bits 0-5 as below),
4) AVDD current (full scale ~1A)
5) AVDD2 current
6) DVDD current
7) HDI temperature (-20 to 100 degrees C)
8) AVDD voltage (full scale ~8V)
9) AVDD2 voltage
10) DVDD voltage
The state
of health byte is defined as follows, for a normal readback:
|
|
bit 5 |
0 |
if 1 channel disabled ( 0
ENABLED!) |
|
|
|
bit 4 |
0 |
if 1 temperature tripped |
|
|
|
bit 3 |
1 |
if 1 HDI enabled |
|
|
|
bit 2 |
0 |
if 1 AVDD current limit
tripped |
|
|
|
bit 1 |
0 |
if 1 AVDD2 current limit
tripped |
|
|
|
bit 0 |
0 |
if 1 DVDD current limit
tripped |
|