On (e.g.) the Agilent U1272A multimeter there's two values shown in the display: - the currently measured value (depends on the position of the rotary switch), and - an additional "secondary" value which is always the current temperature (measured by an internal sensor, not related to where the probes are connected to). No matter where you turn the rotary switch, the secondary display always shows the temperature. However, the value actually transmitted via USB is *not* the exact temperature value the LCD shows; apparently, for whatever reason, there's a factor applied, depending on the position of the rotary switch. This means the P2 channel will show the correct temperature when the rotary switch is in some positions, and an incorrect temperature value when it's in other positions. Also, there's a P3 channel which is a duplicate of P2 and always contains the same value. This should probably be eliminated in the libsigrok driver (some other parsers already seem to do this, see e.g. recv_conf_u124x_5x()). Here's a log of various rotary switch positions and what the multimeter returns for P2 and P3: V~ mode: sr: [00:01.129767] agilent-dmm: Sending 'FETC? @2'. sr: [00:01.161139] agilent-dmm: Received '+2.30700000E+01'. P2: 23.07 °C sr: [00:00.736883] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.768295] agilent-dmm: Received '+2.30700000E+01'. P3: 23.07 °C mV~ mode: sr: [00:00.706697] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.574201] agilent-dmm: Received '+2.30700000E-02'. P2: 0.02 °C sr: [00:00.554571] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.587972] agilent-dmm: Received '+2.30700000E-02'. P3: 0.02 °C V= mode: sr: [00:00.904007] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.936162] agilent-dmm: Received '+2.30700000E+01'. P2: 23.07 °C sr: [00:00.936366] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.978199] agilent-dmm: Received '+2.30700000E+01'. P3: 23.07 °C mV= mode: sr: [00:00.719834] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.751208] agilent-dmm: Received '+2.30700000E-02'. P2: 0.02 °C sr: [00:00.751357] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.783673] agilent-dmm: Received '+2.30700000E-02'. P3: 0.02 °C Ohm mode: sr: [00:00.717016] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.759215] agilent-dmm: Received '+2.30700000E+07'. P2: 23070000.00 °C sr: [00:00.759403] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.790854] agilent-dmm: Received '+2.30700000E+07'. P3: 23070000.00 °C Diode mode: sr: [00:00.918237] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.949544] agilent-dmm: Received '+2.30700000E+01'. P2: 23.07 °C sr: [00:00.949706] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.981251] agilent-dmm: Received '+2.30700000E+01'. P3: 23.07 °C Capacitance mode: sr: [00:00.920665] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.951993] agilent-dmm: Received '+2.30700000E+01'. P2: 23.07 °C sr: [00:00.952151] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.985619] agilent-dmm: Received '+2.30700000E+01'. P3: 23.07 °C mA-A= mode: sr: [00:00.717444] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.750928] agilent-dmm: Received '+2.30700000E+01'. P2: 23.07 °C sr: [00:00.751097] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.786820] agilent-dmm: Received '+2.30700000E+01'. P3: 23.07 °C uA= mode: sr: [00:00.734741] agilent-dmm: Sending 'FETC? @2'. sr: [00:00.766146] agilent-dmm: Received '+2.30000000E-05'. P2: 0.00 °C sr: [00:00.766306] agilent-dmm: Sending 'FETC? @3'. sr: [00:00.808080] agilent-dmm: Received '+2.30000000E-05'. P3: 0.00 °C