Rice Lake 880 Performance Series Indicator/Controller Technical/Service Manual - Manual (Page 104)

98 880 Technical/Service Manual
10.6.3 RS-485 Data Formats
The 880 has a built-in RS-485 software protocol which is enabled when configuring a port’s TYPE as 485. On the
880 only the COM port has hardware support for RS-485 communication.
All RS-485 communication with the 880 is via command and response. An external host must send a command
and wait for a response.
All remote commands are initiated using the data format shown in Figure 10-2:
<STX> <ADDRESS> <COMMAND> <CR>
ASCII 02
decimal
Address of the
receiving indicator
valid range - 0-255
EDP serial command
NOTE: Host must send <CR>, not
<CR><LF>. Failure to use <CR>
renders all indicators unable to
respond to serial commands
ASCII
13 decimal
Figure 10-2. RS-485 Send Data Format
If the initiating device address matches the port address of a 880 on the RS-485 network, that indicator responds.
The responding indicator uses the format shown in Figure 10-3:
<STX>
ASCII 02
decimal
Address of the
transmitting indicator
Response commands from
indicator:
<first line><EOL>
<additional lines><EOL>
<last line><EOL>
where EOL = <CR> or <CR><LF>
(set by TERMIN parameter on the
SERIAL menu)
ASCII 13
decimal
<CR> <RESPONSE> <ADDRESS> <ETX>
ASCII 3 decimal
Figure 10-3. RS-485 Respond Data Format
• Communication with an RS-485 880 is command / response only. An 880 configured for RS-485 cannot print a
ticket or stream continuous data.
• Any valid EDP command can be sent to the 880 when in RS-485 mode.
• If a command is unrecognized or cannot be executed, the 880 responds with ?? wrapped in the RS-485
protocol. For example: <STX><ADDRESS>??<ETX><CR>
• Depending on the command, the <RESPONSE> may include its own termination characters that are sent
before the <ETX><CR>, see the example for the XG command shown below.
• A multi-line response, for example from a DUMPALL command, is wrapped in the header and footer as a total
but each individual line is not.
<STX><ADDRESS><first line> <EOL>

<additional lines> <EOL>

<last line> <EOL><ETX><CR>
Where:
EOL - <CR> or <CR><LF> (set by the TERMIN parameter for the port)