Arbitration for a communications channel can be provided by scheduling a grant for future access to one of a plurality of requestors to a communications channel shared by the plurality of requestors based on an indication of which of the plurality of requestors is granted access to the communications channel during a current access. The calibration information may be stored in permanent memory of the testing device, such that the device is discarded after use of all the test strips in a kit, or it may be stored in a calibration chip accompanying the set of test strips and distributed therewith, thereby enabling re-use of the testing device with a different set of test strips and associated calibration chip. The bias electrodes include an upper split portion and an optically transparent lower portion. The vertical gear member is engaged with the horizontal gear member. The increased number of stitchers per square centimeter reduces the risks for markings on the glass. The method includes the steps of replenishably storing pressure in the storage chamber during the operating sequence, such stored pressure being derived from fluid flow permitted by the valve, and repeatably operating the isolation valve to apply differential pressure to the pistoncylinder device to actuate the remote device.