Echelon LNS DDE Server User Manual

Page 98

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The parameter options are: as follows


-n bool

Specifies whether the client will receive message response

items from the LNS DDE Server even if the data has not
changed from the last time this response was received from
the network. May be set to True or False. If False, data is
reported to the client only if it has changed. If True, a byte

containing an incrementing counter will be appended to each

incoming response. If not specified, the default value
specified in the Messaging Options configuration dialog is

used.
This option may not work as expected for a series of
messages when some messages use '–nTrue' and some use
'–nFalse'. It is recommended that you standardize on

either using this option or not then set it globally using the
Include Sequence Number option in the Network

Configuration Settings dialog.

-t format_name

Specifies a format name to use for formatting the data in the

incoming response. For response messages, the LNS DDE
Server does not automatically determine 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 (for SNVTs and SCPTs), 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.

The completion code can be one of the following:


0 (LON_OK)

The message succeeded.

7 (LON_MSG_FAILED)

The message failed.

10 (LON_TIMEOUT)

The network interface did not respond.

Note: To receive a completion event, you must establish an automatic link on
msg_complete in the DDE Client before sending the request on msg_out (i.e. the

7-6

Receiving and Sending Application Messages

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