Rockwell Automation 1799-DASCII DeviceNet Serial Interface - Manual (Page 27)

DeviceNet Serial Interface Module 27
Publication 1799-IN012B-EN-P - July 2008
Explicit Messages to Receive the Serial Data String (parameters 16, 17, 18)
Parameters 16, 17, and 18 contain the status of the most-recent incoming serial data
string. You can use the data to read the device's ASCII data via the Explicit
Messaging technique.
Parameter 16 holds the most recent received data.
Parameter 17 defines the size, in bytes, of the DeviceNet message to be sent by the
1799-DASCII module to the master.
Parameter 18 holds the record number of the data string in parameter 16 if the
Header option is selected.
Serial Status Byte Description and Transmission
The Serial Status byte is an OR'd bitfield of a number of status and exceptions flags.
IMPORTANT
If you are using a scanner that must receive a constant message length, set its
Rx (receive) value to this number of bytes.
Serial Status Byte
Bit Exception Description
0 Tx I/O
overflow The transmit queue has overflowed resulting in a loss of data. The transmit I/O is full
of data waiting to be transmitted. Some of the data added has been lost. When
space becomes available in the TX I/O, this bit resets.
1 Rx I/O
overflow The receive queue has overflowed resulting in a loss of data. The receive I/O is full
of data waiting to be processed. A new character arrives before the buffer is
emptied, thus setting the overflow bit. The data character is lost. When space
becomes available in the RX I/O, this bit resets.
2 Rx parity error The message has a parity error. One or more of the characters has a parity error.
3 Rx overrun
error A byte that has not been read has been overwritten by another received byte,
resulting in data loss.
4 Rx framing
error When the stop bit of a received character is a logic zero, a framing error occurs.