D2 Dispenser

The D2 Dispenser is a two-valve nanolitre microplate reagent dispenser. It is a UK Robotics product, so the driver and the instrument are developed together — the behaviour described here is the behaviour Revolution implements, not an interpretation of somebody else’s protocol documentation. The driver itself sets no display name, so RevoWeb shows this device by its model catalog name, “D2 v1.4”.

It needs no software installation and no engineer site visit — only power, comms and a browser.

At a glance

Valves	2, easily replaceable, with options for both high and low volumes
Labware	6-well through to 1536-well plates; deep-well plates up to 65 mm tall
Dispense modes	Automatic stop-and-drop, and fly-by (dispense on the fly)
Comms	RS485, with a USB adapter supplied
Footprint	300 × 200 mm, 210 mm high, 2 kg
Revolution control	Run a stored protocol or a per-well CSV, flush a valve, park and unpark the arms, set or measure calibration

Specifications

These are the figures UK Robotics publishes for the D2, beyond what’s in the table above.

Valve supplier	Fritz Gyger AG, Switzerland
Power	6 W standby, 12 W active; 120–230 VAC, 50–60 Hz

The dispense mode is chosen by volume rather than by the schedule: small volumes go out fly-by, while larger ones stop over the well. That is why the same protocol takes markedly different amounts of time on different volumes, and why plate occupancy in a schedule is best measured rather than assumed.

Published dispense-volume limits are not stated as a single range on the product page; the performance examples given there run from 100 nL to 20 µL. Which volumes a given D2 can actually deliver depends on which of the interchangeable valves is fitted.

Supported methods

Dispensing is defined by a protocol — either one already stored for the instrument and named by its ID, or one built at run time from a CSV of per-well volumes.

• Dispense — run a stored protocol by protocol ID, against the plate currently on the device
• Dispense CSV — build a protocol from a CSV file of per-well volumes and run it. The driver sizes the protocol from the labware’s well count and checks the CSV produced the same number of wells before dispensing
• Flush — flush a valve number (1 or 2) with a flush volume (default 100 µL)
• Park arms — park the arms and disable all motors
• Unpark arms — unpark the arms and disable all motors
• Set calibration — load a calibration from a calibration file path (JSON) and store it against the serial ID read back from the connected instrument

On a D2 fitted with a balance, two gravimetric calibration operations are added:

• Calibrate with balance — calibrate a valve number (1 or 2), optionally moving to the balance first (move to balance, default true)
• Calibrate with balance over a range — the same, bounded by a volume range low and a volume range high, to calibrate only the part of the range an assay actually uses

Two of these deserve a note when you are building a schedule.

Dispense CSV is the per-well route, and it is strict on purpose. The plate on the device must have a labware GUID set in Revolution, taken from the UK Robotics labware library, and the well count recorded there must match both the plate in the schedule and the rows in the CSV. Any mismatch fails the operation rather than dispensing into the wrong wells.

Park arms and unpark arms are exposed as operations, but the driver already parks the arms and disables the motors before a mover picks from or places onto the device. Call them explicitly only when a schedule needs the arms parked for some other reason — a lid operation nearby, or a long idle period.

Integration

Revolution talks to the D2 over serial — RS485 through the supplied USB adapter. The driver sets the line parameters itself when the device is added to a system (115200 baud, 8 data bits, no parity, one stop bit, no flow control), so in practice only the COM port number needs choosing.

Labware identity is the part of the integration that is easy to get wrong. Dispensing depends on the plate type in Revolution carrying the GUID of the matching entry in the UK Robotics labware library; without it, both dispense operations fail with a message pointing at the library rather than dispensing to a guessed geometry. The device holds one plate position, so a schedule feeds it one plate at a time.

Prerequisites

• The D2 must be cabled to the Revolution host and its COM port known before the device is initialised.
• Every plate type the D2 will dispense into must have its labware GUID set in Revolution, from the UK Robotics labware library.
• The protocols a schedule calls by ID must already exist for the instrument.
• A calibration must be active for the valve being used; on a balance-equipped unit it can be produced in place with the calibrate operations, otherwise it is loaded from a calibration file.
• Reagent lines must be flushed and the valve appropriate to the intended volume fitted.

Device configuration

Property	Purpose
COM Port Settings	Serial line settings for the port the D2 is on. Defaults are set for the D2, so normally only the port number is chosen
Balance COM Port	On a balance-equipped D2 only: the serial port the balance is on

If you need more of this instrument driven from a schedule, get in touch — the driver is extended on demand.