TM 11-6625-3071-14
3478A
Table 3-6. 3478A Program Codes
Type Program Description
Code
FUNCTION F1 DC Volts
F2 AC Volts
F3 2-Wire Ohms
F4 4-Wire Ohms
F5 DC Current
F6 AC Current
F7 Extended Ohms (see paragraph 3-118).
RANGE R-3 most sensitive range on any function
R-2 30mV DC, or most sensitive range on any other
function
R-1 300mV DC, 3OOmV AC, 300OmA DC, 300mA AC,
or most sensitive range on any other function
R0 3V DC, 3V AC, 3A DC, 3A AC, or most sensitive
range on any other function
R1 30V DC, 30V AC, 30 Ohm, or most sensitive range
on any other function
R2 300V DC, 300V AC, 300 Ohm, or least sensitive
range on any other function
R3 3K Ohm or least sensitive range on any other
function
R4 30K Ohm or least sensitive range on any other
function
R5 300K Ohm or least sensitive range on any other
function
R6 3M Ohm or least sensitive range on any other
function
R7 30M Ohm or least sensitive range on any other
function.
RA Autorange
DIGITS N3 3 1/2 Digits Displayed
DISPLAYED N4 4 1/2 Digits Displayed
N5 5 112 Digits Displayed
TRIGGER T1 Internal Trigger
T2 External Trigger
T3 Single Trigger
T4 Hold Trigger
T5 Fast Trigger (see paragraph 3-116)
AUTOZERO Z0 Autozero Disabled
Z1 Autozero Enabled
DISPLAY D1 Normal Display Operation
D2 Display Text and update Annunciators
D3 Display Text and turn off Annunciators
HOME HO Equivalent to "F1T4R-2RAZ1N4"
COMMAND H1 Equivalent to "F1R-2RAZ1N4T3"
H2 Equivalent to "F2R-2RAZ1N4T3"
H3 Equivalent to "F3R-2RAZ1N4T3"
H4 Equivalent to "F4R-2RAZ1N4T3"
H5 Equivalent to "F5R-2RAZ1N4T3"
H6 Equivalent to "F6R-2RAZ1N4T3"
H7 Equivalent to "F7R-2RAZ1N4T3"
MISC B Read Status of the 3478A in Binary
COMMANDS See paragraph 3-119.
C Calibrate (see Section IV of this manual)
E Read the Error Register. See paragraph 3-1 20.
K Clears Status Register
M Set SRO Mask (Mdd, where dd is the octal code of
the bits)
S Front/Rear Switch Position
(0 = Rear, 1 = Front)
77) can be sent to program the mask. The mask can be
cleared by sending: "MOO". Remember, the mask is
only set to output a Require Service Message (not the
Status Byte) for a certain SRQ condition.
3-105. Clearing Status Register (Status Byte). Bits 2
through 5 and 7 of the register can be cleared by sending
program code "K", and by a device CLEAR message. Bit
0 (Data Ready) is not cleared since it represents the
3478A’s current status (the bit is cleared when the 3478A
outputs its reading). Bit 6 is the SRQ bit which can be
cleared by a Serial Poll or if the SRQ Mask is set to 00.
3-106. Power-On SRQ. This feature is enabled by
setting the Power-On SRQ switch to On (switch #3 on
the rear panel in the up position). When the feature is
enabled, the 3478A Requires Service (generates an
SRQ) each time power is cycled or a reset condition is
generated by the instrument (e.g. due to an instrument
failure or selecting the Self-Test).
3-107. Sending Data to the Display. Up to 12 ASCII
characters can be displayed at a time by the 3478A’s
display. The legal characters are decimal 32 through 95
of the 128 ASCII characters. Only upper case letters
and numbers can be displayed. Lower case letters
generate characters which do not resemble the letters.
Commas, periods, and semicolons can go between
characters. The ASCII characters can be sent in two
different modes. The following paragraphs explain the
two modes.
3-108. In one display mode, the display is continuously
updated. This is enabled by program code "D2" (e.g.
"D23478A DMM" where "3478A DMM" is the message
displayed). In this mode, the annunciators continue to be
updated. If more than 12 characters are sent to the
display, the extra characters are ignored until a control
character is received. If the control character is different
than HT (Horizontal Tab), VT (Vertical Tab), LF (Line
Field), CR (Carriage Return), or FF (Form Feed), a
Syntax Error is generated. A "D2" code locks the display
until a "DI" (Selects Normal Display) is sent, a CLEAR
message is sent, an error condition occurs, or a front
panel button is pressed.
3-109. The other display mode is selected by sending
code "D3". This mode is the same as the previous
mode, except the display is not updated and all
annunciators are turned off. The text on the display
remains on for about 10 minutes and then the display
goes blank. The display can be restored by sending any
of the display codes (DI, D2, or D3) or by pressing the
LOCAL button (if not disabled by the LOCAL LOCKOUT
Message).
3-110. Home Commands. The Home Commands
(when sent to the 3478A over the HP-IB) are used to set
the 3478A into a predefined operating state. The
program code is "Hn", where n is the number which,
3-12
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