Graseby 3000/500, Manual

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G r a s e b y M e d i c a l L t d .
12
3 0 0 0 / 3 1 0 0 a n d 5 0 0 / 5 0 5 S e r v i c e M a n u a l
V o l u m e t r i c I n f u s i o n P u m p s
I s s u e A ( A p r i l 2 0 0 2 )
Record Format - Version 0.67 and below
A record consists of a string of characters that are in a specific order
and follow the rules listed here. A record may in general be any
length up to 47 characters including the record header and other
special characters. The pump uses records with specific lengths
appropriate to the command.
The general record format contains the following fields, summarised in
the table below and explained in detail in the sections that follow it:
< LL C DDD SS >
Field Description
< Record header
LL Record length (2 characters)
C Command code
DDD Command data (variable length)
SS Record cheksup (2 characters)
> Record terminator.
Record Header
As shown above, the first character of any record transmitted is an
ASCII "<" character (3C hex).
This character is always recognised as the start of a new record, so it
must not be included in the command parameter area.
If this character appears in the command parameter area, the
partially assembled record is discarded and an attempt is made to
begin assembling a new record.
Record Length
The second and third characters are made up of the ASCII digits 0-9
and letters A-F, a-f.
This two digit string, with the most significant digit in the second
character position of the record, represents the total character count
of the record being transmitted. The two digits form a hexadecimal
value representing an 8 bit number. The count includes the header,
record length digits, command code, command parameters, checksum
characters and terminator.
• A minimum record will have no parameters; therefore, the
minimum record length is seven characters.
• Maximum parameter length is 40, so the maximum record
length is 47 (2F in hexadecimal).
Command Codes
The fourth character in any record is the command code, which is
transmitted by the host to the pump to tell the pump what
information is required. The pump responds with the same command
in the same character position to verify that the correct command
was executed.