Fluke 8842A

Fluke

8842A

5.5-digit digital multimeter

multimeter Proprietary

Jeff Keyzer, CC BY-SA 2.0, via Wikimedia Commons

Default Address 1

Termination CR LF

IEEE 488.2 No

IDN Patterns

*,8842*,*,*FLUKE*,8842*,*,*

Documentation

• Manual

The Fluke 8842A is a 5.5-digit bench multimeter produced from the mid-1980s. It uses a proprietary command set — NOT IEEE 488.2 or SCPI. There are no *IDN?, *RST, or *CLS commands. Use *? for identification and Y0 for self-test. Commands are single-character codes (F, R, S, T, etc.) followed by a digit. Multiple commands can be concatenated into a single string (e.g., F1R0S0T0). The instrument responds with CR LF terminated readings. The 10A current ranges (F7, F8) use a separate front-panel terminal.

Status Byte

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
Unused	RQS	Syntax Error	Data Available	Overrange	Unused	Unused	Unused
Not used	Requesting service (SRQ asserted)	Command syntax error detected	Reading available in output buffer (MAV equivalent)	Measurement is over range	Not used	Not used	Not used

Read via serial poll. No *STB? or *SRE commands — this instrument predates IEEE 488.2. SRQ mask is set with the SRQ command (e.g., S0 to S63).

Commands

Function Selection

Select the measurement function. Commands take effect immediately.

Command	Type	Description
F1	command	Select DC Volts function
F2	command	Select AC Volts function
F3	command	Select 2-wire kOhms (resistance) function
F4	command	Select 4-wire kOhms (resistance) function
F5	command	Select DC mA (current) function
F6	command	Select AC mA (current) function
F7	command	Select DC Amps function (10A input terminal)
F8	command	Select AC Amps function (10A input terminal)

Range Selection

Select the measurement range. Available ranges depend on the active function. R0 enables autoranging for all functions.

Command	Type	Description
R0	command	Enable autorange
R1	command	Range 1: DCV/ACV=200mV, kOhms=200ohm, mA=200uA
Details Note: Lowest range for the active function
R2	command	Range 2: DCV/ACV=2V, kOhms=2kohm, mA=2mA
R3	command	Range 3: DCV/ACV=20V, kOhms=20kohm, mA=20mA
R4	command	Range 4: DCV/ACV=200V, kOhms=200kohm, mA=200mA
R5	command	Range 5: DCV=1200V, ACV=750V, kOhms=2Mohm, mA=2A
R6	command	Range 6: kOhms=20Mohm (resistance only)
Details Note: Only valid for 2-wire and 4-wire resistance functions (F3, F4)

Rate / Resolution

Set measurement rate, which determines digit resolution. Slower rate yields higher resolution.

Command	Type	Description
S0	command	Slow rate: 5.5-digit resolution, ~2.8 readings/sec
Details Note: Best accuracy and noise rejection
S1	command	Medium rate: 4.5-digit resolution, ~5.6 readings/sec
S2	command	Fast rate: 3.5-digit resolution, ~20 readings/sec
Details Note: Fastest measurement rate

Trigger Mode

Configure the trigger source. Determines when the meter takes a reading.

Command	Type	Description
T0	command	Internal trigger: continuous free-running measurements
T1	command	External trigger: trigger from rear-panel external trigger input
T2	command	GET trigger: trigger via IEEE-488 Group Execute Trigger
Details Note: Use the GPIB GET command (or AR488 ++trg) to trigger a reading
T3	command	Single trigger: take one reading then hold
Details Note: After the reading is taken, meter enters hold state until retriggered
T4	command	Hold: no triggers accepted, measurement suspended

Reading / Output

Request readings and configure output format.

Command	Type	Description
?	query	Request the current display reading
Details Returns (string) — Reading in the selected output format Example: +01.23456E+0 Note: Returns the most recent measurement value
G0	command	Output format: engineering notation with prefix (e.g., +01.23456E+0)
G1	command	Output format: programming format with status and function info
Details Note: Includes status byte, function code, and range code with reading
G4	command	Output format: one-shot — send single reading then stop output
G8	command	Output format: all readings — continuously output every reading

Offset / Null

Enable or disable relative (null/offset) mode. Stores a reference value and subtracts it from subsequent readings.

Command	Type	Description
O0	command	Disable offset (null) — readings are absolute
O1	command	Enable offset (null) — current reading is stored as reference and subtracted from subsequent readings
Details Note: Take a reading with the reference connected before enabling, so the null value captures the current measurement

Suffix

Control whether units suffix is appended to readings.

Command	Type	Description
W0	command	No units suffix on readings
W1	command	Append units suffix to readings (e.g., VDC, VAC, KOHM, MA)
Details Note: Suffix indicates the active measurement function

Display Control

Control the front-panel display.

Command	Type	Description
D0	command	Display on — normal front-panel display operation
D1	command	Display off — blanks the display for faster measurement throughput
Details Note: Disabling the display eliminates display-update overhead and increases reading rate

Beeper

Control the audible beeper.

Command	Type	Description
B0	command	Beeper off
B1	command	Beeper on

System / Identification

Self-test and identification commands.

Command	Type	Description
Y0	command	Execute self-test
Details Note: Runs internal diagnostics. Takes several seconds. Returns error code if a fault is detected.
*?	query	Model identification query
Details Returns (string) — Model identification string Example: FLUKE,8842A,0,0 Note: This is NOT an IEEE 488.2 *IDN? command. The 8842A uses *? as its proprietary identification query.

Compound Commands

Multiple commands can be sent in a single string. The 8842A parses them left to right.

Command	Type	Description
F1R0S0T0	command	Example: Set DC Volts, autorange, slow (5.5 digits), internal trigger
Details Note: Commands can be concatenated without delimiters. The meter parses character-by-character.
F3R3S0T2	command	Example: Set 2-wire resistance, 20kohm range, slow rate, GET trigger

Common Workflows

Measure DC Voltage

Take a high-resolution DC voltage measurement with autorange

1

Select DC Volts function

F1

2

Enable autorange

R0

3

Set slow rate for 5.5-digit resolution

S0

4

Set internal trigger (continuous)

T0

5

Read the measurement

?

Expected: +XX.XXXXXE+X

High-Resolution Resistance

Measure 2-wire resistance at maximum resolution on a specific range

1

Select 2-wire kOhms function

F3

2

Select 20kohm range

R3

3

Set slow rate for 5.5-digit resolution

S0

4

Set internal trigger

T0

5

Read the measurement

?

Expected: +XX.XXXXXE+X

Triggered Measurement (GET)

Configure for Group Execute Trigger and take a single reading on command

1

Select DC Volts and configure (compound command)

F1R0S0

2

Set GET trigger mode

T2

3

Send Group Execute Trigger via GPIB bus

++trg

AR488 command to send IEEE-488 GET to the addressed device

4

Read the triggered measurement

?

Expected: +XX.XXXXXE+X

Fast Continuous Readings

Stream readings at maximum speed for monitoring

1

Select function (e.g., DC Volts)

F1

2

Enable autorange

R0

3

Set fast rate for 3.5-digit resolution (~20 rdg/sec)

S2

4

Turn off display for maximum throughput

D1

5

Set internal trigger for continuous readings

T0

6

Set continuous output mode

G8

7

Read measurements (each bus read returns next reading)

?

Expected: +XX.XXXE+X

8

Re-enable display when done

D0

Null / Relative Measurement

Zero out lead resistance or offset before measuring

1

Select function and range

F3R1S0

2

Connect reference (e.g., short leads for resistance null)

Manual step

Physically short the test leads together

3

Set internal trigger and wait for stable reading

T0

4

Enable offset — stores current reading as null reference

O1

5

Connect the device under test

Manual step

Replace shorted leads with DUT connection

6

Read the nulled measurement

?

Expected: Reading with offset subtracted