PLX3x Series ♦ Multi-Protocol Gateways
ASCII Protocol
User Manual
ProSoft Technology, Inc.
Page 145 of 215
January 25, 2018
8.2.2 Configuring the Port for Receive-Only Mode
In order to set a port for Receive-Only mode, ensure that the
Rx DB Start
parameter in the configuration file contains the starting location where the data
will be stored. The
Tx DB Start
parameter must contain a value of
-1
. This value
indicates that the port will not transmit any data.
8.2.3 Configuring a Port for Transmit-Only Mode
In order to set a port for Transmit-Only mode, ensure that the
Tx DB Start
parameter in the configuration file contains the starting location where the data
will be stored. The
Rx DB Start
parameter must contain a value of
-1
. This value
indicates that the port will not receive any data.
8.2.4 Configuring a Port for Transmit-Receive Mode
In order to set a port to both receive data and transmit data to an ASCII device,
ensure that the
Rx DB Start
parameter and the
Tx DB Start
parameter both
contain values that specify data storage starting locations for received and
transmitted data. A value of
-1
in either parameter disables the particular function
that the parameter serves.
8.2.5 Termination of Received Data
When the PLX3x gateway receives data on the application port, you must define
when this data will be transferred to the internal database in the module. You do
this by setting the termination type for the port. When the termination condition is
met, the gateway sends the data from the port’s receive buffer (data area of 255
bytes) to the internal database. You set the termination type in the bit mapped Rx
Termination Type field of the module object. The following illustration shows the
bit map used for this parameter.
Termination Type Field
Bit(s)
4 to 7
3
2
1
0
Bit Value
-
8
4
2
1
Definition
Reserved
Packet size
limit used
Intercharacter
delay timeout
used
Message
timeout used
Termination
character(s)
used
If none of the bits are set (Type=0), the port is configured for stream mode. Any
characters received on the port are immediately sent to the processor. The
processor must buffer and assemble a packet of information if this mode is
selected as required by the application. If the data can be handled by the
processor in this mode and it is appropriate for your application, this is the fastest
method of communication between the device and the processor.
