Keithley 199 Instruction Manual page 47

BASIC DMM OPERATION
Terminal configuratioix are marked on the circuit board
and connectig blocks. Channel input terminals are mark-
ed CHl through CHS inclusive. Each channel input has
a HI and LO terminal, labelled H and L respectively. Two
sets of output terminals, OUT A and OUT B,+we also
located on the connecting blocks. The output configura-
tion depends on the whether Z-pole or 4-p& mode is to
be used, as discussed below.
WARNING
Maximum common mode voltage (potential
between any contact and earth ground) is 350V
peak. Exceeding this value may create a shock
hazard.
WARNING
User-supplied lethal voltages may be present on
the scanner card terminals.
CAUTION
Maximum scanner signal level is 2OOV, 100mA;
any terminal to earth ground is 350V peak. Ex-
ceeding these values may damage the scanner
card.
Using the Supplied Output Cables
Red and black output cables with banana plugs are sup-
plied with the scanner for convenient connections to the
rear panel input jacks. Prepare and connect these cables
as follows:
1. Ship the ends of the cables =5/W', then twist the
strands together.
2. Connect the red cables to OUT A HI and OUT B HI.
Tighten screws securely.
3. Connect the black cables to OUT A Lo and OUT B La
liihten screws securely.
4. For 2-pole connections, plug the two red cables and two
black cables together, and then plug them into the rear
panel VOLTS~OHMS HI (red) and LO (black) jacks
(Figures 2X4).
5. For 4-pole connections, plug the cables in as shown in
Figure Z-1lB.
Z-pole Connections
Two-pole connections are used for volts and 2-wire
resistance measurements. In order to use the 2-p_ole mode,
the OUT A and OUT B terminals must be connected
together (H to H, L to L) and to the DMM. In the 2-pole
mode, if only OUT A is connected to the DMM input, on-
ly channels l-4 will be routed through the relays. Similar-
ly, channels 5-8 will be available if only OUT B is
connected.
For volts and 2+&e resistance measurements; connect the
outputs to the VOm OHMS terminals (H to HI, L to LO).
The rear panel input jacks are most convenient for this
configuration.
NOTE
Make sure the INPUT switch is set for the rear in-
put terminals.
Figure 2-G shows typical input connections for voltage
measurements. Input connections for 2-wire ohms
measurements are shown in Figure and Z-13.
4-p& Connections
four-pole connections are used exclusively for 4-w& ohms
measurements. With this configuration, the paired chan-
nels (1 and 5,2 and 6,3 and 7,4 and 8) must be connected
to the resistances-under test, as shown in the typical con-
nections of Figure 2-14. The hvo outputs are separately con-
nected to VOWS OHMS and OHMS SENSE terminals us-
iii&the supplied output cables. Note that the two outputs
must not be connected together in the 4-p&e mode.
2-25