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Agilent 34970A — Data Acquisition / Switch Unit

Overview

The Agilent 34970A is a modular data acquisition and switching unit that accepts plug-in cards for analog measurement, digital I/O, totalizing, and DAC output. The driver is organised per card (per slot), not per function: a single card exposes all of its capabilities at once.

Specification Value
Type DAQ / Switch Unit
Interface GPIB, USB-TMC
Cards supported 34901A (20-ch analog mux), 34907A (multifunction: DIO + Totalizer + DAC)
Driver name Agilent34970A
Resource patterns GPIB?*::?*::INSTR, USB?*::?*::INSTR

Channel addressing

Channels use the form sNN where s = slot (1/2/3) and NN = channel within the card. In SCPI lists this becomes a 3-digit number: slot 1 ch 1 → 101, slot 2 ch 16 → 216, slot 3 ch 5 → 305. In this app the slot is written as 100 / 200 / 300.

Supported Cards

34901A — 20-Channel Multiplexer (Analog Input)

  • 20 multiplexer channels: 101…120 (slot 1).
  • 2 dedicated current channels: 121, 122 (built-in shunts) — current is only measurable here.
  • Per-channel function: each channel may measure a different quantity, so one scan can return e.g. 2× DC voltage and 1× 4-wire RTD temperature.
  • Measures: DC/AC voltage, 2-wire/4-wire resistance, DC/AC current (ch 21/22 only), frequency, period, temperature (thermocouple / RTD 2W & 4W / thermistor).
  • 4-wire rule: a 4-wire measurement (FRES / RTD 4W) must use a source channel in 01…10; the instrument automatically pairs it with channel n+10 (11…20), which must not appear separately in the scan list.
  • Built-in isothermal reference junction for thermocouples.
  • Max 250 V channel-to-earth.

34907A — Multifunction Module (DIO + Totalizer + DAC)

Fixed channel assignment — do not confuse these (mixing them up causes instrument error 305):

Channel Function
s01 Digital I/O port 1 (8-bit)
s02 Digital I/O port 2 (8-bit)
s03 Totalizer (26-bit pulse counter, up to 100 kHz)
s04 DAC output 1 (±12 V, 16-bit)
s05 DAC output 2 (±12 V, 16-bit)

So for slot 1: DAC1 = 104, DAC2 = 105, totalizer = 103, DIO ports = 101 / 102.

SCPI commands used

Operation Command
Detect card in a slot SYSTem:CTYPe? {100\|200\|300}
Configure a channel CONFigure:<func> [<range>[,<res>]],(@<ch>)
Configure temperature CONF:TEMP {TC\|RTD\|FRTD\|THER},<type>,(@<ch>)
Define scan list ROUTe:SCAN (@<ch_list>)
Initiate + read a sweep READ?
Set DAC output SOURce:VOLTage <volts>,(@<s04\|s05>)
Write digital byte SOURce:DIGital:DATA:BYTE <data>,(@<s01\|s02>)
Read digital byte [SENSe:]DIGital:DATA:BYTE? (@<s01\|s02>)
Read totalizer MEASure:TOTalize? READ,(@<s03>)
Clear totalizer [SENSe:]TOTalize:CLEar:IMMediate (@<s03>)
Read error queue SYSTem:ERRor?
Integration time [SENSe:]<func>:NPLC <n>,(@<ch>)
Mx+B scaling CALCulate:SCALe:GAIN/OFFSet/UNIT/STATe …,(@<ch>)
Trigger source TRIGger:SOURce {IMMediate\|TIMer\|EXTernal\|BUS\|ALARm}
Scan interval (timer) TRIGger:TIMer <seconds>
Sweep count TRIGger:COUNt <n>
Channel delay ROUTe:CHANnel:DELay <seconds>,(@<ch_list>)

Mixed-function scanning works because the instrument keeps a per-channel configuration: the driver sends one CONF:… per channel, then a single ROUT:SCAN over the whole list, then READ?. Values are returned in scan-list order.

Connecting

  1. Power on the 34970A with cards installed.
  2. Add the instrument, select the GPIB/USB resource and connect.
  3. Click WYKRYJ KARTY (Detect cards) on the front panel — the driver queries SYST:CTYP? for each slot and fills in the detected card types.

Front Panel

Tabs are built dynamically from the cards in the slots — one tab per installed card. The sidebar handles card configuration: WYKRYJ KARTY (auto-detect) or manual per slot.

34901A multiplexer tab

  • Editable grid: each row = a channel chosen from a slot-aware dropdown + function + range. Mixed functions in one scan (e.g. 2× VDC + 1× RTD 4W).
  • The grid enforces the card rules live:
    • a channel already used in one row disappears from the dropdowns of the other rows (each channel can be configured only once),
    • selecting a current channel (s21/s22) restricts that row's function list to CURR_DC/CURR_AC (and auto-switches the function); other channels hide the current functions,
    • configuring a row as 4-wire (OHM4W/TEMP_RTD4W) reserves the source channel and its n+10 pair, so both vanish from the other rows.
  • Konfig. kanału… opens a dialog for the selected row: resolution, NPLC, and Mx+B scaling (gain M, offset B, custom unit).
  • Konfig. skanu… opens a dialog for scan settings: trigger source, timer interval, sweep count, channel delay.
  • Single scan, continuous scan (UI poll interval), and a results grid with auto-sized, resizable columns.

34907A multifunction tab

All three functions of the one card on a single tab (no slot selector — the tab is the card):

  • DAC1 / DAC2 with set-point, ▲/▼ step buttons (configurable step), and Set.
  • Digital I/O — both ports shown side by side (port 1 = s01, port 2 = s02), each with read indicators and write toggles.
  • Totalizer — read / reset.

Sequence Blocks

Block Purpose
Wykryj karty (A34970A_DetectCards) Run SYST:CTYP? and configure detected cards.
Skanuj kanały (A34970A_ScanChannels) Scan a channel list with one shared function.
Skan mieszany (A34970A_ScanMixed) Mixed per-channel scan. Spec format: kanał=FUNK[:param][@zakres] separated by ;, e.g. 101=VDC; 102=VDC@10; 103=RTD4W:85; 104=TC:K.
Zmierz kanał (A34970A_MeasureChannel) Measure a single channel (slot + channel + function).
Ustaw DAC (A34970A_SetDAC) Set a DAC output (channel s04/s05), −12…+12 V.
Cyfrowe wyjście (A34970A_SetDigitalOutput) Write a byte to DIO port 1 or 2.
Cyfrowe wejście (A34970A_ReadDigitalInput) Read a byte from DIO port 1 or 2.
Odczyt totalizatora (A34970A_ReadTotalizer) Read the totalizer count, optionally reset after.

Mixed-scan spec — function names

VDC, VAC, OHM2W/RES, OHM4W/FRES, IDC/CURR_DC, IAC/CURR_AC, FREQ, PER/PERIOD, TC (param = type letter, e.g. K), RTD (param = α: 85/91), RTD4W/FRTD (param = α), THERM (param = 2200/5000/10000).

Example Sequence — Mixed Measurement Scan

[Start]
→ [A34970A_DetectCards, Instrument=DAQ]
→ [Loop N=10, counter=i]
    ↓ body
    [A34970A_ScanMixed, Instrument=DAQ,
       Spec="101=VDC; 102=VDC; 103=RTD4W:85", Prefix=ch]
    → [AddToChart, Series="RTD", Variable=ch_103]
    → [Wait 5000ms]
→ [SaveCsv, Path="C:\Data\scan.csv"]
→ [End]