SERIES
9900
9000
SERIES
GAUSSMETERS
APPENDIX continued
Programming Information
normally looks like <ESC>ME100000000<CR›. Replacing the "0"s with a
specific ASCII character string such as <ESC>MElabcdefgh<CR> the
gaussmeter will return the command exactly as you sent it, if the channel is
offline. The "abcdefg" will be replaced with the actual field information, as
described in this manual, if the channel is online.
4) In any application program involving communication with external
devices it is a good idea to incorporate an escape route in the event a
device fails to function properly. When programming the gaussmeter's
setup parameters (MODE, RANGE, etc.) allow enough time for the
gaussmeter to execute the command and return the response before
declaring a timeout and reissuing the command. Each setup operation can
take several seconds to execute before the gaussmeter returns the
response. The more operations there are in one single command string,
the longer it will take to receive a response. For a single MEASURE or
LOCKOUT command the gaussmeter can return a response within several
milliseconds.
RS-232 PROGRAMMING INFORMATION
1) When using the RS-232 port use one of the two cable configurations
depicted in this manual. The use of parity checking is highly
recommended. We have found that some PCs power-up with their RS-232
handshake lines in a FALSE state. I f you are using a cable with full
handshaking this may present a problem unless your software makes these
lines TRUE. The use of the cable
without
handshaking is suggested if in
doubt. Using a cable with just TX, RX and GND will not work.
2) There is a certain amount of time that is required for the gaussmeter to
return a response command. When calculating an appropriate timeout
value remember to include the baud rate lag time. The time it takes to
transmit each character (not each string) is:
TIME (seconds) -
1 + D + S + P
BAUD
where: D = number of data bits
S = number of stop bits
P = 0 for no parity or
1 for odd/even parity
A single MODE command at 1200 BAUD, 7 data bits, odd parity, one stop
bit will require a minimum of 50 milliseconds to transmit.
Remember, baud
rate only describes the rate at which each character is transmitted and not
the time it takes the computer to load each character into the transmit
buffer.
3) When issuing a ZERO or RELATIVE command the gaussmeter will
transmit an XOFF (hex 13) when it first enters the operation and an XON
(hex 11) when it finishes, and
then
returns the response. The gaussmeter
also transmits XOFF and XON any time it performs a recalibration
sequence. Your progam should be prepared for these control characters.
See the section of this manual dealing with software handshaking.
IEEE-488 PROGRAMMING INFORMATION
1) When using the IEEE-488 bus,
always
read the gaussmeter's response
string whether or not your wish to use it. The gaussmeter will remain idle
until the response is read. Remember that a TRIGGER command is
required after you output a command string to the gaussmeter.
54
