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56 - Configuring a Serial Port DeviceMaster PNIO | UP User Guide : 2000639 Rev. A
Configuring a Serial Port
Oversize Rx
Packets
• Truncate - Oversize packets are truncated and sent to IO
controller as cyclic IO data.
•
SaveRec
- Oversize packets are truncated and sent to IO
controller as cyclic IO data. The original packets are also
saved as acyclic record data.
• Drop - Oversize packets are dropped.
Serial Port Configuration - Serial Packet
Rx Detect
Delimiters from
Serial Device
Start of
Transmission
(STX)
When enabled, the DeviceMaster detects an STX (start of
transmission) byte sequence which is configured as
one byte
or
two bytes
when it receives a serial packet.
The length indicates the number of STX bytes, valid values for
length are:
•
none
- Disables this function and the DeviceMaster accepts
the first byte received after the last ETX byte(s) as the
start of the next data packet.
•
one byte
- Scans serial data for one STX byte and when the
DeviceMaster finds an STX byte it collects the data. If the
first byte is not the STX byte, it discards the byte. The
DeviceMaster continues to discard the bytes until it finds
an STX byte.
•
two bytes
- Scans serial data for two STX bytes and when
the DeviceMaster finds two STX bytes it collects the data.
If the STX bytes cannot be found, it discards the bytes. The
DeviceMaster continues to discard the bytes until it finds
the two STX bytes.
Byte 1
- Specifies the character that represents the first STX
byte. The DeviceMaster looks for this character in the first STX
byte, if the length is
one byte
or
two bytes
. You can specify a
value between 0 and 255 in decimal format.
Byte 2
- Specifies the character that represents the second STX
byte. The DeviceMaster looks for this character in the second
STX byte, only if the length is
two bytes
. You can specify a value
between 0 and 255 in decimal format.
Serial Port Configuration - Serial Device Options (Continued)