Fluke 2180A - Manual (Page 67)

21X0A-004
Option -004
IEEE-488 Interface
604-1. INTRODUCTION
604-2. Option 21X0A-004 IEEE-488 Interface provides
the 2180A and 2190A digital thermometers with a direct
output only connection to the IEEE-488 bus.
604-3. Option 21X0A-004 may be ordered with the 2180A
and 2190A thermometers for factory installation, or is
available by itself for service center installation. Option
21XO A-004 cannot be used in a 2300A Scanner system. For
more compatibility information, refer to “Compatibility
With 2300A and Previously Produced Thermometers”.
604-4. The IEEE-488 standard connector is accessible
from the rear panel of the thermometer. The format of the
output data includes the channel number, the current read­
ing, and any out-of-range or open thermocouple informa­
tion. (Refer to Table 604-3.)
604-5. SPECIFICATIONS
604-6. Specifications for Option 21 XO A-004 are shown in
Table 604-1.
NOTE
The L4 listener function indicates that the
thermometer IEEE-488 bus interface has the
same 5-digit talk and listen addresses, and that
the receipt of a listen address disables the talk
address.
604-7. IEEE-488 BUS ADDRESS CODE
SELECTION
604-8. A six-position dip switch (SW3), located on
Option 21X0A-004 pea (printed circuit assembly), sets the
IEEE-488 bus address codes for the option. To gain access
to SW3, lift off the case top of the thermometer by remov­
ing the six screws from the base. Referring to Table 604-2,
set positions 1 through 5 of SW3 to assign the desired
address.
604-9. OPERATION
604-10. Once Option 21X0A-004 is installed and SW3 is
properly set, make sure that the IEEE-488 cable is correctly
connected to the option to ensure that all functions are
properly monitored by the controller.
604-11. Program Considerations
604-12. Position 6 on SW3 controls the SRQ signal (Ser­
vice Request) to the IEEE-488 bus. Upon receiving an
SRQ, the controller serially polls each device on the bus for
SRQ status. SRQ status of the Option 21X0A-004 is indi­
cated by bit DB6 (position 64 decimal, 40 hexadecimal) in
the serial poll register (U12). With SW3 position 6 in the
ON position, SRQ is generated when a LF (line feed) is
received in the 32-byte buffer of Option 21X0A-004. The
LF character is used by the thermometer to indicate the end
of a data transfer to the Option 21 XO A-004. (Refer to Table
604-3.) Option 21X0A-004 sets DBl (2 decimal), which
causes a serial poll to return a total value of decimal 66 or 42
hexadecimal.
604-13. When the SRQ mode is enabled, the SRQ is set
when the thermometer makes a reading available to the
Option 21X0A-004. The reading is held indefinitely until
the SRQ is serviced. All new readings from the thermom­
eter are discarded. When SRQ is disabled, the output
buffer is continuously updated with the most recent reading
from the thermometer. However, there may be a 0.33
second delay encountered in the returned reading. This
delay occurs when one reading is sent across the IEEE bus
and the Option 21X0A-004 waits for the thermometer to
send the next reading. An IEEE bus timeout error may
occur unless the timeout is set longer than this delay.
604-1