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2
2.10
ANALOG & DIGITAL CONNECTIONS
The 4807/2307/4867/2367's Analog and Digital Signals are on connector
J2. Connector J2 is a 62-pin high-density DC shell connector with lock
studs. Available mating connectors include solder eyelet and poke-in pin
type connectors. Table 2-9 lists J2's signal-pin assignments.
2.10.1 Digital I/O Lines
There are 32 Digital I/O lines that can be configured as inputs or outputs in
groups of 8 lines. The eight line groups can be combined (configured)
together to form larger input or output groups when more than 8 lines are
required or addressed as separate eight bit bytes. The 32 digital I/O lines are
controlled by four 8-bit bidirectional latches. Data direction is referred to
as output when the digital lines output data is received from the GPIB or
Serial bus. Data direction is input when data is read in from the digital lines
and is talked onto the GPIB bus or outputted serially.
The simplest data transfer is done with the port commands that address a
specific Digital I/O byte or port. Data polarity can be set on a bit-by-bit basis
with the port polarity commands. The data bytes used with the port
commands should not be configured as inputs or outputs.
String commands or transparent data strings transfer data to or from one or
more bytes that are selected as inputs or outputs by the configuration
commands. Data format and polarity is the same for all configured output
or input bytes. The string commands always transfer data in a left-to-right
fashion.
The data format command lets the user represent each byte as a decimal
number or as two hex characters as listed in Table 2-9. The bytes on the
digital interface are numbered 1 to 4. Data transfer for input or output
strings is in the ascending byte count direction which is the same as the MSN
to LSN nibble direction. This is the natural way people write a string of
characters from left to right, i.e. 1234. The user can assign multiple bytes
into Talk (input) or Listen (output) strings, or leave the bytes unassigned.
Bytes assigned to strings by the configuration commands must be assigned
in numerical order and can start with any byte number (i.e. 1, 2, 3 or 4).
When string commands are used to transfer data, the data polarity and
conversion format settings apply to all of the input or output bytes.
Paragraph 2-11 shows some sample signal assignments.
