Owner`s manual

34
1.4.5 V74 EIA-232 SERIAL MODULE
OPERATION
The V74 4-port EIA-232 serial module will
simultaneously multiplex incoming data from connected
peripheral devices (e.g., bar code readers, digital
laboratory instruments, etc.). The V74 allows the host
computer to individually select any peripheral device and
send data to the selected device. The V74 has four
modes of operation.
Full duplex reporting mode provides full duplex
communication between the host computer and a
selected peripheral device. Data received by a non-
selected V74 port is buffered until selected by the host
computer.
Immediate message mode provides automatic message
multiplexing. A message begins when a port on the V74
module receives a character from the device connected
to it. A message is completed when a user
programmable terminating character is received or 2048
characters have been received without a terminating
character. Each message sent to the host controller can
be preceded by a port identification code consisting of
the Unit#:Module#,Port# or the device name of the port
that received the message. Immediate reporting mode
sends messages to the user automatically as they come
in to the V74 module.
Immediate data mode is similar to immediate message
mode. The primary difference is that immediate data
mode does not wait for a message terminating character
to send data to the designated host module. Data is
sent to the designated host module automatically as
soon as it is received by any port on the peripheral
communication module.