The LCD screens have two fields, "Gen" and "Comb" which display the last Master General pressed and last Scoped Piston pressed. Hauptwerk automatically sends that information out the status port. These pistons are found by going to View > Large floating control panels > Registration.
Hautpwerk does not automatically send the information for the general and divisional pistons from each sample set (i.e the ones on the screenshots provided by the sample set maker). If you wish to map the sample set's general and divisional pistons to "Gen" and "Comb", you will have to program the output for each individual piston for each sample set.
The process is, as follows:
1) Right-click (Control-click for Macs) on the piston you wish to configure (or move to the next piston in the list if you already have the configuration page open)
2) Click on "Adjust MIDI/trigger settings manually for..."
3) Click on Input 2 tab and autodetect the physical switch that you wish to control the onscreen piston (even if you have already done this before) and follow the instructions.
Here's why we're doing this: The only configuration screen that allows us to send the message we need to send to the screen is the Primary Output tab. In order to make the Primary Output settings send out the MIDI port, we have to configure the Primary Input screen. What we program into the Primary Input screen is not a message you can assign to any piston. So, we are configuring the hardware input for your piston on Input 2.
This means, if you ever want to change the physical piston that you're using for control, you'll have to use the procedure from step 3 to map the piston to the software.
4) Click on the Primary Input tab.
5) Click on the Primary Output tab and select "Auto MIDI output (match to primary input settings) from the "Output" dropdown list. Select your output device (CLASSIC ORGAN CMK3 in this example) or "any enabled port" from the "MIDI OUT port" dropdown list.
6) Click on the Primary Input tab. Here's where all the work is.
Set the "Input" to "Generic MIDI sys-ex constant messages"
Set the MIDI IN port to "any enabled port" or to your MIDI interface.
There is a box under the "MIDI Channel" field. Scroll down in that box until you see the "('On') sys-ex bytes" area.
Fill in bytes 1-6 in the "('On') sys-ex bytes column" as shown.
Byte 4 - refers to the message type sent. 022 (hex 01) corresponds to "Last Master General Pressed" ("Gen" onscreen). When doing divisionals, you'll change that to 056 (hex 38) to correspond with "Last Scoped Piston Pressed" ("Comb" onscreen). More on "Comb" later.
Byte 5 refers to the Generals 1-20. Below you see it set to 001 (hex 01). This sends the number one to the LCD display for Gen. So, for General Piston 1, you should probably set byte 5 to 001 (hex 01).
002 (hex 02) will send the number "2" to the LCD screen. 003 will send "3". 020 will send 20.
7) Once you have completed steps 1-6, for General Piston 2 you can test it out by going to Primary Output and clicking on the "Test: send 'on'" button. You won't see much if you do this after General Piston 1 because the screen defaults to showing 1 anyway.
Variations for configuring "Comb"
Steps 1-5 are exactly the same for configuring a sample set's divisional pistons to work with the screen. The variation comes in step 6 on the Primary Input tab.
Bytes 1-3 and 6 are identical to configuring Gen.
However, byte 4 on the Gen configuration used 022 (hex 16), for the Divisional pistions, you will use 056 (hex 38).
Byte 5 has this configuration.
001 - 010 - Scoped Piston A1-A10
011 - 020 - Scoped Piston B1-B10
021 - 030 - Scoped Piston C1-C10
031 - 040 - Scoped Piston D1-D10
041 - 051 - Scoped Piston E1-E10
051 - 060 - Scoped Piston F1-F10
001 - 060 are part of the normal stream of messages that Hauptwerk automatically sends out the status port. They correspond to the scoped pistons found in Hauptwerk's Organ Settings > MIDI/Key Triggers for Master Pistons and Menu Functions for This Organ > Registration: master general xx.
In order to accommodate users who are setting the Comb field to work with the sample set's native combination action, we have included an extended list that incorporates the name of the division. Note, this cannot be used with Hauptwerk's native Master Scoped Pistons because they have the A-F naming system.
061 -070 - Gt1- Gt10
071 - 080 - Sw1-Sw10
081 - 090 - Ch1-Ch10
091 - 100 - So1-So10
101 - 110 - Pd1-Pd10
111 - 120 - Ma1-Ma10
121 - 127 - Ac1-A