CDN36X User Manual
revision 1.30
Serial Channel Interface
The CDN36X serial channel consists of an asynchronous serial transmitter and receiver. The
serial interface is configured and controlled by the
Serial Stream Object, Serial Receive Object,
and
Serial Transmit Object
.
Serial Stream Object
The
Serial Stream Object
attributes configure the serial channel’s baud rate, number of data bits
and stop bits, parity, and flow control. This configuration applies to both the serial transmitter
and receiver. The gateway has separate 128-byte serial transmit and receive FIFO buffers,
allowing full duplex operation when supported by the physical layer media.
The
Serial Stream Object
also scans incoming serial data for valid message packets. A message
packet is determined by one of three
Delimiter
modes.
List
mode searches for
Pre-Delimiter
and
Post-Delimiter
byte strings at the beginning and end of a message.
Length
mode captures a
specific number of message bytes, defined by
Packet Length
.
Timeout
mode uses an inter-byte
delay (
Packet Timeout
) to signal the end of a message. When a message packet is received, it is
processed by all enabled
Serial Receive Object
Instances. The following examples show the
three
Serial Stream Object Delimiter
modes.
0x45 0x62 0x02 0x31 0x32 0x32 0x42 0x45 0x03 0x0D 0x11 <delay> 0x43 0x56 …
Incoming data stream
0x02
0x31 0x32 0x32 0x42 0x45
0x03 0x0D
List Mode (delimiters)
Pre-Delimiter Message
Packet Post-Delimiter
0x45 0x62 0x02 0x31 0x32 0x32 0x42 0x45
Length Mode (fixed #bytes)
Message Packet
Packet Length = 8
0x45 0x62 0x02 0x31 0x32 0x32 0x42 0x45 0x03 0x0D 0x11
Timeout Mode (inter-byte delay)
Packet Timeout = 100 msec
Message Packet
MKS Instruments, Inc.
D.I.P. Products Group
13