Comtrol UP DeviceMaster User Guide - Manual (Page 70)

70 - Chapter 3. Embedded Configuration Pages DeviceMaster UP Modbus/TCP User Guide: 2000447 Rev. I
Serial Packet Identification
ETX (End of
Transmission)
Rx Detect
When enabled, the DeviceMaster UP detects an ETX (end of transmission) byte
sequence that is configured as one byte or two bytes marking the end of the serial packet.
The length indicates the number of ETX bytes, valid values for length are:
• none - Disables this function and the DeviceMaster UP uses the Rx Timeout Between
Packets to indicate the end of data packet.
• one byte - Scans serial data for one ETX byte and when the DeviceMaster UP finds
the ETX byte, it identifies the data as a serial packet.
• two bytes - Scans serial data for two ETX bytes and when the DeviceMaster UP finds
the ETX bytes, it identifies the data as a serial packet.
Byte 1 - Specifies the character to scan for in the first ETX 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 to scan for in the second ETX byte, if the length is two
bytes. You can specify a value between 0 and 255 in decimal format.
Discard Rx Pkts
with Errors
By default, this box is checked and the DeviceMaster UP discards serial packets with
errors. Clear the check box when you need to receive a serial packet with errors to
troubleshoot an issue.
PLC Specific Settings and Application Specific Settings
STX Tx Append
When enabled, the DeviceMaster UP appends an STX (start of transmission) byte
sequence which is configured as one byte or two bytes to the beginning of the serial packet
before it is sent.
The length indicates the number of STX bytes, values for length are:
• none - Disables this function.
• one byte - Inserts one STX byte before the data.
• two bytes - Inserts two STX bytes before the data.
Byte 1 - Specifies the transmit character associated with 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 transmit character associated with the second STX byte, if the
length is two bytes. You can specify a value between 0 and 255 in decimal format.
ETX Tx Append
When enabled, the DeviceMaster UP appends an ETX (end of transmission) byte
sequence which is configured as one byte or two bytes to the end of the serial packet
before it is sent.
The length indicates the number of ETX bytes, valid values for length are:
• none - Disables this function.
• one byte - Inserts one ETX byte at the end of the data.
• two bytes - Inserts two ETX bytes at the end of the data.
Byte 1 - Specifies the transmit character associated with the first ETX byte, if the length
is set to one byte or two bytes. You can specify a value between 0 and 255 in decimal
format.
Byte 2 - Specifies the transmit character associated with the second ETX byte, if the
length is two bytes. You can specify a value between 0 and 255 in decimal format.
Strip Rx STX/
ETX
When you select this check box, the DeviceMaster UP strips STX/ETX characters from
received serial packets. Clear the check box when you do not want the DeviceMaster UP
to strip STX/ETX characters from received serial packets.
Serial Packets sent from the PLC or application to the DeviceMaster UP (over Ethernet),
and then sent out the serial port, are not checked for STX/ETX.
No STX/ETX character stripping occurs in these serial packets, and framing/parity/
overrun error checking does not apply.
Serial Port Packet Identification (Continued)