User guide

3 Installation Model 3020M
3-10
Teledyne Analytical Instruments
DTR 4 Data Terminal Ready
COM 5 Common
DSR 6 Data Set Ready
RTS 7 Request to Send
CTS 8 Clear to Send
RI 9 Ring Indicator
The data sent is status information, in digital form, updated every two
seconds. Status is reported in the following order:
• The concentration in percent
• The range in use (HI, MED, LO)
• The span of the range (0-100 %, etc)
• Which alarms—if any—are disabled (AL–x DISABLED)
• Which alarms—if any—are tripped (AL–x ON).
Each status output is followed by a carriage return and line feed.
Four input functions using RS-232 have been implemented to date.
They are described in Table 3-4.
Table 3-4: Commands via RS-232 Input
Command Description
as<enter> Immediately starts an autospan.
az<enter> Immediately starts an autozero.
st<enter> Toggling input. Stops/Starts any status message output from
the RS-232, until st<enter> is sent again.
The RS-232 protocol allows some flexibility in its implementation.
Table 3-5 lists certain RS-232 values that are required by the 3020M imple-
mentation.
Table 3-5: Required RS-232 Options
Parameter Setting
Baud 2400
Byte 8 bits
Parity none
Stop Bits 1
Message Interval 2 seconds