Rockwell Automation 1799-DASCII DeviceNet Serial Interface - Manual (Page 23)

DeviceNet Serial Interface Module 23
Publication 1799-IN012B-EN-P - July 2008
Produce Received-serial Data onto DeviceNet Network
Received-string Data Type (parameter 10)
The format of the data is Array, Short_String,
or String - sent to the DeviceNet master, as
shown below. Choose the one best suited for
your application and that modifies the format
of the data field.
The format of the data sent to the 1799-DASCII module is Array, Short_String, or
String. Choose the one best suited for your application and modifies the format of
the data field.
The Array data type has no length associated with it. It is equivalent to specifying a
length of zero by using a string or short_string data type.
The Short_String data type is the default data type of the device. This suffices for
most applications. The Short_String data type has only 1 byte of length, and the
rest of the data bytes are appended after the length.
The String data type has 2 bytes of length. The String data type is useful in talking
to programmable controllers or other devices that have a data file specifically made
to handle this data type. The length is Little Endian (low byte, high byte), and the
high order byte should be set to zero. The 1799-DASCII module only receives up
to 250 bytes of information, so the extra byte, although required for this data type,
is 0.
Received-string Data DeviceNet Assembly Formats
The following tables define the format that the 1799-DASCII module produces on
DeviceNet network and sends to the DeviceNet master. In all cases, the size of the
assembly is equal to the length of the received ASCII string plus a 4-byte header.
IMPORTANT
If the Short_String or String data type is used, the length is not sent to the
ASCII device.
Produce Data DeviceNet Format - Array String Type
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5-X (250 bytes max)
Transaction ID Status byte Reserved Reserved ASCII data (including optional <terminator>.