LXE 1280 Reference Guide

118

Message Format

LDS Plus Reference Guide

E-SW-LDSPLUSRG-G

Sequence Number (SEQ #)

Note:

SEQ # is not applicable to Protocol messages.

Sequence numbers enable the receiving device to determine if a message is a duplicate. In other
words, sequence numbers prevent the host computer or DOS terminal from acting upon the same
message twice.

Sequence numbers always occupy the first text position of a message. The DOS terminal accepts
any sequence number other than the last one received. The sequence numbers are printable
characters: A-Z, a-z, 1-7.

Sequence number 0 (zero) is sent to the host (for the first send) when the Power Up Message is
displayed. The send can be manually activated by pressing the [Enter] key, so PowerUpMessage
does not have to be set to “Yes”.

Rule: If the DOS terminal is to receive sequence numbers, the LDS Plus

parameter RcvSeqNumbers must be set to Yes.

Rule: If the DOS terminal is to generate sequence numbers, the LDS Plus

parameter AutoSeqNumbers parameter must be set to Yes.

See Chapter 3, “Configuration Utility”.

The message format below highlights the location of an outbound sequence number character:

SOL ID1 ID2 TYPE

CTRL

N/EF

SEQ #

TEXT EOL

Figure 4-17 Location of Sequence # Character in an Outbound Message

Here is an example of an outbound message showing the location of the sequence number:

is the sequence

number.

<02SQC

Part Number is Invalid)C

Figure 4-18 Outbound Message with Sequence Number

The message format below highlights the location of an inbound sequence number character:

SOL ID1 ID2 TYPE

CTRL

SEQ #

TEXT EOL

Figure 4-19 Location of SEQ # Character in an Inbound Message

See also “Control Character (CTRL).” Control characters in an inbound message indicate to the
host whether the message is a form or non-form message and if the message includes a sequence
number.