OHAUS 7000 Series, Руководство по обслуживанию

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APPENDIX B COMMUNICATIONS
7000 Series T72XW Indicators Service ManualB-17 Ohaus Corporation www.ohaus.com
B.18 Variable Access
All setup parameters and a few triggers and statuses in the terminal are available through a
connection called “Variable Access”. This is a serial interface assignment on COM1that permits
remote clients to send and receive commands and data from the terminal.
B.18.1 Connection
In order to access the variables in the T72XW terminal, the COM1 port must be used and it
must be assigned as Variable Access in the connection menu of setup.
Make sure the serial port of the remote device matches the parameters selected for the COM1
port. This includes the baud rate, data bits, parity bit, and 1 stop bit.
Connect an RS-232 cable between the remote client PC and the COM1 port of the T72XW
terminal.
Open a program to communicate with the terminal (such as HyperTerminal). Refer to the
Commands section to understand how the commands should be structured.
B.18.2 Commands
The T72XW supports two commands - Read and Write. Some variables are read only and some
can be both read and written. A response is always sent after a Read request or a Write
command. If a valid format and variable are requested in a Read, Response 1 from below will
be sent. If the format is incorrect or a bad variable name is requested, an error like Response 2
will be sent. A Write command will receive either an acknowledge (ASCII <ACK> - 06xh) for an
accepted command or a negative acknowledgement (ASCII <NAK> - 15xh) for an invalid
command or data.
A Space character is required between the index number and data that is being sent. This
characters is shown as <SP> (20xh) in the examples. All commands and responses are
terminated with a Carriage Return and a Line Feed character. These characters are shown as
<CR>< LF> (0Dxh, 0Axh).
B18.3 Individual Variables
The PC program can connect with the T72XW terminal to read and write specific variables per
the following examples. The list of index numbers is given in the next section.
Read request: R(index#)<CR><LF>
Read filter value: R129<CR><LF>
Response 1 (valid): R129<SP>1<CR><LF>
Read filter value: R1 7 9<CR><LF>
Response 2 (error): R1 7 9<SP> Error: Invalid
Request<CR><LF>