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PLX3x Series ♦ Multi-Protocol Gateways ASCII Protocol
User Manual
ProSoft Technology, Inc. Page 141 of 215
January 25, 2018
Transmit-Only Mode
A port on the module configured to function in transmit-only mode only transmits
data from the gat
eway’s internal database (received from an external source or
mapped from upper memory) to an ASCII device. When the transmit driver (Tx
Driver) recognizes a new write block containing data in the module’s internal
database, it transmits this data out to the port. The sequence number in the block
is different that that of the previous block. This signals that the packet is fully
assembled and ready to send. The following illustration shows flow of data on a
port configured for transmit-only mode.
Transmit-Receive Mode
A port configured in transmit-receive mode can send and receive data from an
ASCII device (for example, a terminal). This mode functions in both the transmit
and receive modes. Data flow to and from an ASCII device is handled by the
module’s transmit and receive drivers.

Data received from the ASCII device is stored in the module’s internal
database until ready to be sent to an external device.

Data received by an external device is also stored in the module’s internal
database until ready to be transmitted to the ASCII device.
The following illustration shows the flow of data on a port configured for transmit-
receive mode.