Echelon LNS DDE Server - Manual (Page 95)

-t type_name Specifies a format name to use for formatting the message
data as described in the next section. If this option is not
specified, a format is selected by LNS. Use this option and
specify a format name to change the format. The format
name can be one of the five built-in formats (INTEGER,
DISCRETE, REAL, STRING, or RAW), a format name from the
standard resource file, or a format name from any user
resource file. If the format name is RAW, data will be
returned in raw format.
When changing the data format using this parameter, the
change is applied to the entire data value. This may cause
unexpected results. For example, when reading a network
variable which is a floating point value, and changing the
format to an integer (-t INTEGER), the formatted value will
be an integer interpretation of the entire floating point
number, not just the integer part. The same thing applies
when changing the data type to floating point (-t REAL) for
an integer value. Make sure formats are compatible with the
network variable value.
Note:
Floating point values must be between –3.4E38 and
+3.4E38.
Specifying a Request Message
When the LNS DDE Server sends a message using the REQUEST service type on the
msg_out item, it expects the destination device or devices to send response messages
back in reply. If the request message was sent using one of the unicast (i.e.
subnet/node) addressing modes (described later in this chapter), only one response
message will arrive. If the request message was sent using a multicast addressing
mode, one or more devices may respond.
Use the MT topic to receive response messages sent in response to an outgoing request
from the LNS DDE Server. Within the MT topic, the LNS DDE Server uses the
following item format for receiving response messages:
[device_name.]resp_in[.msg_code] [parameters]
Where each component of the item format has the following meaning:
device_name
Optional. Specifies the name of an application device, as
defined in the LNS database. If not specified, the item
specifies all incoming responses addressed to the LNS DDE
Server host PC.
resp_in Required. resp_in is a keyword, not a user-defined name.
This keyword is case insensitive.
LNS DDE Server User's Guide 7-3