User's Manual

545C Operations Manual

02/10/2012 Prerelease DCN 00001789-A

Ad Hoc Connection

A connect string from 1 to 19 characters is used to open a connection on an

ad hoc basis. The connection will remain open for as long as characters are

being received or the connection times-out, whichever occurs first. Once

the connection times-out it must be reestablished.

If the connect string is unknown, the command ANY will open the

connection for any string of characters.

Connect Response

A connect response string may be enabled so that the peripheral device

initiating the message will receive confirmation that the connection has

been made. If the connect response string is turned OFF then no response

will be sent when the connection is made.

Message Management

A message may be as long as 3,500 characters. Each message is assigned a

sequence number and is broken up into a number of packets. A message

header is inserted into each message ahead of the first data character.

$DIR,p,m,s,n

where: p = the assigned port to which the message is directed.

m = the message sequence number from 1-2554

s = the packet sequence number in a multi-packet message

n = total number of packets in a message

A message will be appended with either a terminator character or a

maximum character count. The message will be terminated by either one

of these characters or the “time-out” whichever occurs first.

Shorter messages are normally contained in a single packet with the s,n

parameters set for 1,1. Longer messages will have several packets

contained within the same message number “m”. The “s” parameter for

each packet will be incremented but the “n” parameter will be set to 0.

The true “n” value is only transmitted with the last packet in the message.

For example, for a 3 packet message the s,n and m parameters will be as

follows: