Specifications

Remote Programming – Command List
48
computer is not asserting the DTR line on the
RS-232.
COMMON SOFTWARE PROBLEMS
INCLUDE:
1) You have sent the wrong command to ask for
data from the SR400. Your program will wait
forever for a response which is not going to come.
This may not be your fault; we have seen
Microsoft's Interpreted Basic on the IBM PC
occasionally send a curly bracket (ASCII 253)
when it was supposed to have sent a carriage
return (ASCII 13).
2) Your computer's baud rate has been changed
and no longer matches the SR400's baud rate.
3) The initial command sent to the SR400 was
invalid due to a garbage character received during
power-up, or, the first character in your computer's
UART is garbage, also due to power-up. It is good
practice to send a few carriage returns to the
SR400 when your program begins, and have your
program clear-out the UART at the start of your
program.
4) The SR400 is not sending the correct 'end-of-
record' marker for your computer. For example, it
appears that Microsoft's Rev 3.2 FORTRAN on
the IBM PC under DOS 2.1 requires two carriage
returns for an end-of-record marker. The SE
command can be used to set the SR400 end-of-
record marker to 2 carriage returns. [The end-of-
record marker is that sequence which indicates
that the response is complete. From the keyboard,
a single carriage return is the end-of-record
marker.]
5) Answers are coming back from the SR400 too
fast, overwriting the end-of-record markers, and
causing the computer to hang, waiting for a
complete response. In this case, the SW command
can be used to slow down the response time of the
SR400 preventing overwriting.
6) Answers are coming back from the SR400 too
slowly due to the RS-232 wait interval being too
large. Use the SW0 command at the beginning of
your program to speed up the transmission from
the SR400.