Brooks Instrument 0254 - Manual (Page 95)

C-17
Model 0254
Section C Serial Communications Protocol Installation and Operation Manual
X-SE-0254-eng
Part Number: 541B129AAG
September, 2010
C-4-5-1 Message Structure
A packet is a group of information from channel input ports. A group of
packets sent together is a block message, as shown in the examples
below. Protocol responses are compatible with existing published protocol
formats. Frames noted below as lower case 'x' remain <reserved>,
regardless of frame content.
MESSAGE
AZ,00909.00,2,xxxxxxxx.xx,00162871.43,-0000003.27,xxxxxxx.xx,xxxxx,X,X,X,X,X,<sum><cr><lf>
C-4-5-2 Message Format
BLOCK PRELIMITER
<dle><stx> Start of multi-port block
PACKET PRELIMITER
AZ Start of a port packet
ADDRESS - unit and port(s) providing the information
,xxxxx unit address
.xx port sub-address
TYPE - message purpose
Un-polled Types
,0 <reserved>
,1 <reserved>
,2 <reserved>
,3 <reserved>
,6 <reserved>
Polled Types
,4 Information request response
,5 Control batch status
,6 <reserved>
,7 <reserved>
,8 <reserved>
,9 <reserved>
MEASURE - channel input port values - sign convention as (+), space(+), or minus(-)
,xxx <reserved>
,QTY Quantity
,RATE Rate-Value
,xxx <reserved>
,xxx <reserved>
CHECKSUM
,<sum> Negated mod256 sum
PACKET DELIMITER
<cr><lf> Packet end