Comtrol UP DeviceMaster User Guide - Manual (Page 21)

DeviceMaster UP Modbus/TCP User Guide: 2000447 Rev. I Chapter 2. Programming Interface - 21
Instance Attribute Definitions
Attribute 11
PLC Transmit ETX
Append Value
You can set this attribute to append an ETX (end of transmission) byte sequence
which is configurable as 1 or 2 -bytes to the end of the serial packet before it is sent.
The length indicates the number of ETX bytes. The valid values for length are:
• 0 (zero) - Setting this attribute to zero disables this function.
• 1 (one ETX byte) - Inserts one ETX byte at the end of the data.
• 2 (two ETX bytes) - Inserts two ETX bytes at the end of the data.
• Value - Specifies the transmit character associated with the first ETX byte. (Only if
the length is not zero.) You can specify a value between 0 and 255.
• Value2 - Specifies the transmit character associated with the second ETX byte.
(Only if length is 2-bytes.) You can specify a value between 0 and 255.
Attribute 13
Receive STX Detect
Value
This attribute detects an STX (start of transmission) byte sequence which is
configurable as 1 or 2-bytes when it receives a serial packet.
The length indicates the number of STX bytes. The valid values for length are:
• 0 (zero) - Setting this attribute to zero disables this function. When disabled, the
DeviceMaster UP accepts the first byte received after the last ETX byte(s) as the
start of the next data packet.
• 1 (one STX byte) - Scans serial data for one STX byte. If the DeviceMaster UP finds
an STX byte it collects the data. If the first byte is not the STX byte, the
DeviceMaster UP discards the byte. The DeviceMaster UP continues to discard
the bytes until the DeviceMaster UP finds an STX byte.
• 2 (two STX bytes) - Scans serial data for two STX bytes. If the DeviceMaster UP
finds two STX bytes it collects the data. If the first two bytes are not the STX
bytes, the DeviceMaster UP discards the bytes. Bytes continue to be discarded
until the DeviceMaster UP finds two STX bytes.
• Value1 - Specifies the character that represents the first STX byte. DeviceMaster
UP looks for this character in the first STX byte. (Only if the length is not zero.)
You can specify a value between 0 and 255.
• Value2 - Specifies the character that represents the second STX byte.
DeviceMaster UP looks for this character in the first STX byte. (Only if length is
two bytes.) You can specify a value between 0 and 255.
Attribute 14
Receive ETX Detect
Value
This attribute detects an ETX (end of transmission) byte sequence which is
configurable as 1 or 2 bytes marking the end of the serial packet.
The length indicates the number of ETX bytes. The valid values for length are:
• 0 (zero) - Setting this attribute to zero disables this function. When disabled, the
DeviceMaster UP uses the Receive Timeout Between Packets (attribute 15) to
indicate the end of data packet.
• 1 (one ETX byte) - Scans serial data for one ETX byte. When the DeviceMaster UP
finds an ETX byte it identifies the data as a serial packet.
• 2 (two ETX bytes) - Scans serial data for two ETX bytes. When the DeviceMaster
UP finds two ETX bytes it identifies the data as a serial packet.
• Value1 - Specifies the character to scan for in the first ETX byte. (Only if the length
is not zero.) You can specify a value between 0 and 255.
• Value2 - Specifies the character to scan for in the second ETX byte. (Only if length
is 2-bytes.) You can specify a value between 0 and 255.
Attribute 15
Receive Timeout
Between Packets
This attributes specifies:
• How long DeviceMaster UP waits (in milliseconds) if the Receive ETX length is
not zero (0) and it does not receive an ETX byte sequence.
• The time to wait (in milliseconds) between serial packets if the Receive ETX
Detect length is set to zero (0).
Attribute Description