Kurt J. Lesker 979 Series, Operation And Maintenance Manual

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Series 979 ATV Transducer 23
RS-485 Protocol
The 979 supports 2400, 4800, 9600, and 19200 baud rates (factory
default: 9600). The data format is 8 data bits, no parity, and one stop bit.
Standard Addresses
Valid addresses are 3 digits, 001 to 253 (factory default: 253).
Universal Addresses
The 979 receives and responds to commands sent to address 254. For
example, use 254 to communicate with a device if its address is unknown.
The 979 receives and acts upon commands sent to address 255, but does
not respond; use 255 to broadcast messages to multiple devices attached to
the same system. For example, use 255 to change the baud rate for all
devices.
Query and Command Syntax
Queries return current parameter settings; commands change the parameter
setting according to the value the user types in the command syntax. Each
query or command must begin with the attention character @ and end with
the termination string ;FF.
Syntax required for a query is:
@<device address><query>?;FF.
Syntax required for a command is:
@<device address><command>!<parameter>;FF.
Examples:
Query current baud rate: @253BR?;FF
Change baud rate to 19200: @253BR!19200;FF
where:
@ attention character
253 <device address>
BR? <query>? (for query syntax)
BR!19200 <command>!<parameter> (for command syntax)
;FF terminator