Keysight Technologies L4490A, Руководство пользователя

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Keysight L4490A/L4491A User’s Guide 149
Additional Operating Information
You do not need to provide an external current limiting resistor.
L4490A/L4491A Digital IO and Relay Driver Option 004
The following sections contain additional information on the digital (general
purpose) IO and relay drive option to the RF switch platform.
Digital I/O Functions
The Digital input/output (DIO) channels (2001, 2002) each provide an 8-bit byte
of DIO, which may be accessed separately or combined together to form one
16-bit word. In addition to these 16 bits, the P102 connector contains three
output-only control lines (pins 22-24 - Chapter 4) that are always enabled. These
lines represent the handshake sequence that regulates read/write data transfers
(Figure 5-8).
Data Read Sequence
When reading data on the input as with the command:
SENSe:DIGital:DATA[:<width>]? [<format>,] (@<ch_list>)
control line 3 (read/write status line - pin 24) is set high. If the read target is byte
1 (channel 2001), control line 1 is set strobe low, the byte 1 data is read, and then
control line 1 is set strobe high. The strobe pulse width is 3.75
3
s, and the time
from strobe low to valid data is 1.25
3
s.
Similarly, if the read target is byte 2 (channel 2002), control line 2 is set strobe
low, the byte 2 data is read, and then control line 2 is set strobe high. The strobe
pulse width is 3.75
3
s, and the time from strobe low to valid data is
1.25
3
s.
If both bytes (channels 2001 and 2002 combined) are targeted as a word, both
control lines 1 and 2 are set strobe low, both bytes (16-bits) are read on the
input, and both control lines are set strobe high. The strobe pulse width is longer
(5
3
s) than for a single byte read, but the time from strobe low to valid data is still
1.25
3
s.
In all three instances, once the data has been read, the data lines are left in
tri-state (indeterminate).
The LEDs obtain their power from the power supply of the
34945EXT module. If command:
ROUTe:RMODule:DRIVe:SOURce OFF
has been sent, the LEDs will not operate. Refer to Chapter 2 for
additional information on LED connector pin definitions and
cabling.