Vaisala RVP900, Руководство пользователя

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There is an option for having a "Fault Status" input on the "D" connector of the DAFC. Since
the board is completely passive in its connection to the uplink, the fault status bit does not
affect the uplink in any way. The bit is received by the board (with optional polarity reversal)
and driven onto the terminal block (P3), from whence it can be wired to some other device,
for example, a BITE input line of an RCP02. A yellow LED indicates the presence of any
external fault conditions.
The "AB" position of the 3-pin "Alarm" jumper (H9) connects the Fault Status signal to Pin
#4 of the terminal block, whereas the "BC" position grounds that terminal block pin. A
second ground can be made available at Pin #5 of the terminal block by installing a jumper
in the "BC" position of the "Spare" 3-pin jumper (H10). This second ground could be used as
a ground return, when the Fault Status line is driven off of the terminal block. The "AB"
position of the "Spare" jumper is reserved for some future input or output line on the
terminal block.
A crystal oscillator is used to supply the operating clock for the on-board logic, and there
are two choices of frequency to use. If jumper H2 is "Off", the crystal frequency should be
equal to the IFD sampling clock f
aq
, and if H2 is "On", the frequency should be (0.75 × f
aq
).
More Information
‣
Digital AFC (DAFC) (page 50)
4.4.1 Example: Hookup to a CTI MVSR-xxx STALO
Here is a complete example of what would need to be done in hardware and software to
interface the DAFC to a Communication Techniques Inc. digital STALO.
The electrical interface for the STALO is through a 26-pin ribbon cable, which carries both
Control and Status, as well as DC power. This cable can be crimped onto a mass-terminated
25-pin "D" connector (with one wire removed) and plugged directly into the DAFC. The
following table shows the resulting pinout.
The STALO frequency is controlled by a 14-bit binary integer, whose LSB has a weight of 100
KHz. The
Inhb pin must be low for the STALO to function. Power is supplied on the +5 V
and +24 V pins, and two grounds are provided. An "alarm" output is also available.
Table 24 Pinout for the CTI MVSR-xxx STALO
Ribbon Pin "D" Pin Function Ribbon Pin "D" Pin Function
1 1 Ground 2 14
--
3 2 +5V 4 15
--
5 3 +24V 6 16
--
7 4 Alarm 8 17
--
9 5
--
10 18 Bit-0
11 6 Bit-2 12 19 Bit-1
13 7 Bit-3 14 20 Bit-10
Chapter 4 – RVP Hardware
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