Measurement Computing

Category

Data acquisition

Kind

source

Capabilities

StreamsAssetsCommandsOperationsEntities

Runs on

Linux x64Linux ARM64Windows x64

Read analog inputs, digital lines and counters, and set analog and digital outputs, on Measurement Computing USB and Ethernet DAQs.

Windows and Linux only. It uses the Universal Library (cbw64.dll, installed with InstaCal) on Windows and uldaq on Linux. There is no macOS build: MCC publishes no macOS library.

#What you get

• Analog inputs — the channels you list, such as ai0, ai1, timed by the board's own clock.
• Digital inputs — one line as 0/1 (FIRSTPORTA/0, AUXPORT/3, or di<n> for bit n of the first port), or a whole port as an integer (FIRSTPORTB).
• Event counters — such as ctr0 on a USB-201, as running totals since the input started.
• Outputs — the board's analog outputs (±10 V) and every digital line and port it can drive, set from Trellis via ch.write(path, value). A line takes true/false (/mcc/mcc1/AUXPORT/3); a port takes an integer (/mcc/mcc1/FIRSTPORTB). A USB-201 has no analog output. Every write is recorded, and a line write is read back from the board.
• Any number of boards in one input, named by its Device name. Channels read /mcc/mcc1/…. The primary board uses bare names (/mcc/mcc1/ai0). Other boards appear in the same table and use their id (/mcc/mcc1/21A3DAC/ai0) once you tick their channels. Boards line up by this computer's clock, since each has its own oscillator.

#Setup

1. Install the MCC library and connect the device: InstaCal / Universal Library on Windows, uldaq on Linux. Phloem detects a USB board and offers a draft with its serial filled in. The steps below are the manual path.
2. In Inputs, add Measurement Computing and fill in:
   • Device name — a short label, e.g. mcc1 or engineA. Every channel is named under it. Renaming it later moves the channels' calibration, names, tiles, pipelines and setups with them, after you confirm. Past recordings keep the old name, and Replay shows "previously …" beside the channel. From the CLI: phloem input rename-prefix "<input>" engineA.
   • Unique ID — the serial number. Leave empty for the first device found. On Windows, board:0 picks the board number InstaCal gave it, including a DEMO-BOARD, which works with no hardware.
   • Input channels — e.g. ai0,ai1, or tick them in the table. It lists every analog input, digital line and port the board can read. A USB-201 shows ai0..ai7 and AUXPORT/0..7; the DEMO-BOARD shows AUXPORT, FIRSTPORTA and FIRSTPORTB, eight lines each.
   • Sample rate — starts at the board's own default. The DEMO-BOARD offers 1000 Hz per channel with a 300 000 Hz ceiling; a 100 S/s module starts at 100.
   • Digital & counter poll rate — how often digital lines and counters are read.
3. Press Test connection. It names the board, its number of analog inputs, and its rate range.
4. Inputs appear on Live. Outputs are available in Trellis.

#Sample rate

• The board's clock sets the timing. The stream states the rate the board actually settled on, which may differ slightly from what you asked.
• Rates past the board's limit are refused, including the total across all channels in one scan. For example: *"8 channel(s) at 50000 Hz each asks for
  400000. Lower the sample rate to 37500 Hz"*.
• If a board does not report a limit, the field uses a safe default and shows no limit.
• A stated ceiling is what the board accepts, not a guarantee. The DEMO-BOARD holds 300 kS/s across eight channels within 0.3 %, but only an eighth of that on one channel, because it is a software simulator.
• Only ticked channels are scanned. ai0,ai7 scans two channels, not the eight between them. A board that cannot do this scans the whole range and says so.
• Digital lines, ports and counters are read on this computer's clock at the Digital & counter poll rate. Every rate display shows that rate for them, so a 50 Hz limit switch beside a 12.5 kHz scan reads 50 Hz.
• Live shows which clock timed each channel: backdated for the board's scan, host for this computer.
• Boards with no hardware clock — USB-TC, USB-TEMP, USB-TC-AI, USB-TEMP-AI, USB-2001-TC, USB-TC-32 and E-TC — are read on this computer's clock and marked host.

#Triggers and clocks

• Start trigger — trigger = start=rising waits for the board's trigger input.
• External sample clock — not supported, and refused. The MCC libraries cannot report the real sample period under an external clock.
• Sharing this board's clock — clock = pacer_out=on drives this board's clock out so another instrument can follow it.

#Range and over-range

• The range field sets the ± volts. Leave it empty for ±10 V where the board has it, or its only range. A range the board lacks is refused, with the list it does have.
• Over-range — readings at either end of the converter's scale are marked as one under_range or over_range span, like DAQami's OVR. The span closes once readings stay off the end for 3 s.

#Stopping

Stop ends the acquisition after a number of samples per channel, or after a duration. The input then shows finished.

#Checks before saving

Save, phloem apply and apply --dry-run refuse settings the board cannot take: a channel it lacks (ai9 reads "this board has ai0..ai7"), an unknown line or counter, a scale that does not parse, or a trigger level on a digital start. A board on another machine is not checked, so its project still opens. What only the open board can answer, such as a missing trigger, is refused at start.

#Notes

• Without the MCC library, the connector says so and names the file it looked for.
• There is no watchdog. If this computer stops, outputs stay where they were set. Do not use it to hold a hazardous actuator. Use a PLC or FPGA with its own failsafe.
• A stalled scan is reported. If the board reports RUNNING but sends nothing for twenty blocks (at least two seconds), the connector marks a gap and logs mcc: scan stall #n — the board reports RUNNING and has transferred nothing for N s…. It keeps trying in case the board resumes.
• Matched against DAQami 4.2.1's help and the USB-200 series datasheet.

#Supports

• Measurement Computing USB/Ethernet DAQs via uldaq on Linux (USB-1208, USB-1608, E-1608, ...)
• On Windows via the MCC Universal Library (cbw64.dll), including InstaCal-configured boards
• Replaces DAQami: the same device, acquired live into Phloem

#Connection fields

Every field the Add input form shows for this connector.

Updated November 6, 2026