Allen-Bradley POINT I/O 1734-232ASC

Publication 1734-UM009A-EN-P - June 2002
2-26 Configuring Your RS-232 ASCII Module
Transmitting Serial Data
The length of the string sent determines the use of a delimiter in
transmitting data to a serial device from the 1734-232ASC module.
• If the string length is zero (as dynamically defined by the third
and fourth bytes in the message header), or if the data type is
Array:
The 1734-232ASC module receives data sent from the DeviceNet
master and uses the delimiter to determine how much data is
sent to the serial device. The 1734-232ASC module will compute
the length and then store this as the new length in the string
attribute. (This will not show up if the data type is array, you
will just see the string truncated, and the length will be in the
background.)
• If the string length > 0 or the data type is String or Short_String:
The 1734-232ASC module receives data sent from the DeviceNet
master ignoring any embedded terminator. It will store the
number of characters defined in
Max_Number_of_Transmit_Chars, or the total sent by the master,
whichever is less.
The 1734-232ASC module will send the information immediately in
Transmit Immediate mode. You can always cause the data to be
transmitted by changing the TX ID.
Setting Up the Scanner I/O Transmit Size
The 1734-232ASC module automatically calculates the number of
bytes it will receive from the DeviceNet master. Its value is determined
by a combination of the incoming data and the options you have
selected. Parameter 23 defines the size of the DeviceNet message to
be sent to the 1734-232ASC module from the master and should be set
as the Tx size in your Scanner’s I/O set-up.
IMPORTANT
You must set your scanner’s Tx (transmit) value to
this number of bytes. Remember to upload this data
from the 1734-232ASC module to current information
or put your RSNetWorx for DeviceNet into Monitor
Mode.