14. message format, 16. sample programs, 18. srq program – Fluke 2180A User Manual

Page 68: 20. the non-srq program, 22. group execute trigger

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21X0A-004

Table 604-1. Option 21X0A-004 Specifications

ENVIRONMENTAL

Operating Power

100, 200, 220, 240V ac ± 10% 50/60 Hz, 3VA. (The 12-volt
battery operation is not supported.)

Operating Temperature

40°C (Outside ambient of thermometer.)

OPERATIONAL CONTROL

Switch 3 (SW3)

OUT-OF-LIMIT-SIGNAL

Exclamation point transmitted with Option 21X0A-006
installed only; not with Y2002.

OUTPUT

Protocol and Connections

IEEE-488 standard

IEEE-488 Interface Function Capability Codes

IDENTIFICATION

FUNCTION

CAPABILITY

SHI

Source Handshake

Full

AHI

Acceptor Handshake

Full

T6

Talker

Serial Poll (not talk only)

L4

Listener

Not listen only (see note)

SRI

Service Request

Full

DTI

Device Trigger

Full (see 604-22. for function description)

604-14. Message Format

604-15. Table 604-3. contains the sequence of information
in the output data string. The sequence is the fixed length
format presented on the IEEE bus.

604-16. Sample Programs

604-17. The following sample programs show two differ­
ent situations in which the controller receives temperature

readings from the thermometer. The program listed in Fig­
ure 604-1 instructs the controller to asynchronously retrieve

a temperature reading after an SRQ has been sent from the
thermometer. The program listed in Figure 604-2 instructs
the controller to ask for a temperature reading at a specific
program step.

604-18. SRQ Program

604-19. The SRQ program, when typed into a 1720A,

1722A, or 1752A controller informs the controller what to

do when an SRQ is received from the thermometer. The
program allows the controller to perform other tasks until
the thermometer has a temperature reading. The thermom­
eter sends a 66 hexadecimal value back to the controller in

response to the serial poll (SPL). If more than one ther­
mometer or more than one other instrument (a maximum

of 14) is connected to the controller, the program distin­

guishes which instrument is sending the SRQ and deter­

mines priority if more than one SRQ is received at the same
time. After the controller receives the temperature reading
and prints it on the controller screen, the program ends the
SRQ handling procedure and waits for another SRQ.

NOTE

The following programs are written in Fluke

BASIC and operate on the 1720A, 1722A, and

1752A controllers. A modification of the SRQ

program may be required to conform to other

IEEE controllers.

604-20. The Non-SRQ Program

604-21. The sample program in Figure 604-2 inputs and
prints temperature readings without the use of an SRQ. A
2-second delay is required after the TRIG @2 statement
(line 50) to allow Option 21X0A-004 to finish the reset pro­
cess before requesting readings from it. The TIMEOUT

delay (line 70) must be set greater than 333 ms, so the con­
troller waits for the thermometer to provide the next read­
ing to the INPUT statement.

604-22. Group Execute Trigger

604-23. The Option 21X0A-004 responds to the IEEE-

488 GET command by simply resetting the two micropi ^-
cessors (U5 and Ull) on the board. Resetting the microp-

604-2

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