SERIES
9900
9000
SERIES
GAUSSMETERS
SECTION
V
continued
T
h
e
user should always wait for a "NOT BUSY" condition before issuing
commands to the gaussmeter.
Remote (Slave) Mode Operation
When the host system's bus controller sends a command string to the
gaussmeter, the gaussmeter must be programmed as a listener at the
gaussmeter's preprogrammed primary address (via the COMMUNICATIONS
FORMAT menu). It is not necessary to assert the EOI (End or Identify) control
line when the final terminator character is transmitted, but
the GET (Group
Execute Trigger) command MUST be issued by the system controller before
the gaussmeter will begin executing the command string.
When the gaussmeter is ready to return the command string, it will assert the
SRQ (Service Request) line. The serial poll status register will have its 'rsvl' bit
(0107) set and all other bits reset as follows:
0108 D 1 0 7 0 1 0 6 D 1 0 5 0 1 0 4 D 1 0 3 D 1 0 2 D 1 0 1
0
1
The gaussmeter must then be programmed as a talker before it will transmit
the command string back to the host. The gaussmeter
will
assert the EOI line
when the final terminator character is transmitted.
When the gaussmeter is first powered on, its IEEE-488 interface will be
disabled for about 40 seconds while the gaussmeter performs internal
diagnostics and configuration. Assertion of the REN (Remote Enable) line by
the system controller has the same effect as issuing the LOCKOUT
command.
Issuing the COMMUNICATIONS FORMAT command to modify the IEEE-488
device address can have disastrous results if not properly used. If this
parameter is changed, the system controller's address reference must be
changed to match the new address or
the communications link can be
severed!
Remember that the command string sent to the gaussmeter will not
be executed until the final terminator character is received. When the
COMMUNICATIONS FORMAT command is processed and executed, the
change takes effect immediately. The gaussmeter will return the command
string using the
new
IEEE-488 address. See Appendix for additional
programming information.
V-F R S -232 IMPLEMENTATION
NOTE: It is important to remember that the gaussmeter returns to the
MASTER mode once it executes a SLAVE command. This means that the
gaussmeter will resume transmission of the MASTER mode data table
immediately after sending back the SLAVE response. If the user's program is
not prepared for this, the SLAVE response may be lost. To prevent this,
issue the LOCKOUT-ON command before starting SLAVE operations. This
command (Section V-B (I) terminates the MASTER mode. From this point the
only information transmitted by the gaussmeter will be the SLAVE response.
Issuing the COMMUNICATIONS FORMAT command to modify the RS-232
port characteristics can have disastrous results (the loss of communications) if
not properly used. If any of the parameters are changed, the host DTE's
parameters must be changed to match the new characteristics
or the
communications link will be severed! Remember that the command string
sent to the gaussmeter will not be executed until the final terminator character
is received. When the COMMUNICATIONS FORMAT command is processed
36
