Kenton has released the GPMX-16 Midi-to-GPI/GPI-to-Midi converter, allowing access to the GPI (General Purpose Interface – IEEE-488) short-range digital communications bus vis Midi.
The bi-directional GPMX-16 Midi-to-GPI and GPI-to-Midi converter provides 16 GPI inputs and 16 GPI outputs, arranged across four standard 9-pin D-sub connectors – sockets for inputs (labelled GPI 1-8 In and GPI 9-16 In) and plugs for outputs (labelled GPI 1-8 Out and GPI 9-16 Out). When inputting a manual switch signal into a digital circuit, the signal needs to be debounced so that a single press does not appear as multiple presses – in the case of the GPMX-16, the debounce value for all switch inputs can be set between one to 100ms (defaulting to 10ms) to ensure that this does not happen.
The GPI inputs themselves are arranged with internal pull-ups, so shorting an input to ground will send the appropriate Midi On message and releasing the short to ground will send a Midi Off message (unless disabled). The GPI outputs are floating and can switch up to 50V at 100mA of resistive load. They can also be controlled by Midi On and Off messages or provide a pulse of settable length in response to just Midi On messages (by default).
Each block of eight GPI inputs and outputs can be assigned a Midi starting number, and subsequent inputs and outputs follow on consecutive note numbers (defaulting to 36-43 for the first block and 44-51 for the second). Midi channels can be set independently for the GPI inputs and outputs (defaulting to transmitting on Channel 1 and receiving on Channel 2).
As well as offering control of GPI outputs using Midi, the Midi In socket allows several GPMX-16 Midi-to-GPI and GPI-to-Midi converter boxes to be daisy-chained (without any limit to the number of units that can be daisy- chained as the data is regenerated rather than being merely copied). Any data received at the Midi In socket is merged with any new data generated from the GPI inputs and everything is subsequently sent to the two Midi outputs (Midi Out and Midi Out 2) carrying identical information. A second Midi output has been thoughtfully provided so that data can be sent to a backup computer system at the same time as supplying a primary one.
The GPMX-16 can receive and output Midi messages as Note, Controller (CC), or Program Change data when operating in normal operating mode. It also has additional parameters that can be edited and stored when it is put into edit mode (using a screwdriver or pen to press the recessed front panel-positioned Edit button and adjacent InC, DEC, and Select buttons to receive and display different types of Midi messages). Such settings are stored in EEPROM (Electrically Erasable Programmable Read-Only Memory) for future use.
The unit also has a built-in Midi analyser for displaying types of Midi messages being transmitted, doubling up an already well-specified Midi utility box as a diagnostic tool.
More: www.kentonuk.com
