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 ,
regardless of frame content.
MESSAGE
AZ,00909.00,2,xxxxxxxx.xx,00162871.43,-0000003.27,xxxxxxx.xx,xxxxx,X,X,X,X,X,
C-4-5-2 Message Format
BLOCK PRELIMITER
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
,1
,2
,3
,6
Polled Types
,4 Information request response
,5 Control batch status
,6
,7
,8
,9
MEASURE - channel input port values - sign convention as (+), space(+), or minus(-)
,xxx
,QTY Quantity
,RATE Rate-Value
,xxx
,xxx
CHECKSUM
, Negated mod256 sum
PACKET DELIMITER
Packet end