Hi All
A happy new year to everyone 
Something has been bugging me for a while, so I have spent an hour finding a solution.
What I wanted to do was mimic the Press and Hold dimming / volume change that you might see in some hardware.
I found a way to detect a button event, get the current Item state (a number) and add or subtract a number then inject the new value back into the Volume or Dimmer Item.
This worked well, I had 2 buttons.
1 for up
1 for down
I could even use the Long_Press and Release states from these buttons to loop the trigger so that holding the button down kept on having an effect, until the button was released.
What I wanted to do was reduce this down to 1 button, that would increase the volume (or brightness) until a limit was hit, then decrease until another limit was hit.
I found the solution by using a Global Value in Node Red.
Here is what I have running now in a Function node 
var volume = Number(msg.payload.state);
var button = String(msg.payload_in);
var newMsg = { payload:button};
var Dir = global.get("LoungeDir");
var newVolume = 0;
// newVolume = volume + 5;
msg.payload = volume;
if (isNaN(Dir)) {
global.set("LoungeDir", 1);
Dir = global.get("LoungeDir");
}
if (volume <= 6 ) { if (Dir == -1) {
newVolume = volume + 5;
msg.payload = newVolume;
global.set("LoungeDir", 1);
return [msg,newMsg];
}}
if (volume <= 90 ) { if (Dir == 1) {
newVolume = volume + 5;
msg.payload = newVolume;
// global.set("LoungeDir", 1);
return [msg,newMsg];
}}
if (volume >= 90 ) { if (Dir == 1) {
newVolume = volume - 5;
msg.payload = newVolume;
global.set("LoungeDir", -1);
return [msg,newMsg];
}}
if (volume <= 90 ) { if (Dir == -1) {
newVolume = volume - 5;
msg.payload = newVolume;
// global.set("LoungeDir", 1);
return [msg,newMsg];
}}
return [msg,newMsg];
Here is the entire collection of Nodes
[
{
"id": "bfe462be.f71a5",
"type": "function",
"z": "f5370db.29be5f",
"name": "Dining Room Btn 3",
"func": "var event = msg.payload.event;\nvar channel = msg.payload.channel;\nvar newMsg = { payload: msg.payload.event };\nvar button = \"velbus:vmbgp2:c5053467:24:input#CH3\"\n\nif (channel === button ) {\n\tif (event === \"PRESSED\") {\n\t\treturn [msg, newMsg, null, null];\n\t}\n\tif (event === \"LONG_PRESSED\") {\n\t\treturn [msg, null, newMsg, null];\n\t}\n\tif (event === \"RELEASED\") {\n\t\treturn [msg, null, null, newMsg];\n\t}\n}\nreturn null;",
"outputs": 4,
"noerr": 0,
"x": 390,
"y": 140,
"wires": [
[],
[
"6ba85279.a48a9c"
],
[
"82c396c8.6ef1d8"
],
[
"f7ff8751.3c9c78"
]
],
"outputLabels": [
"Whole Msg",
"PRESSED",
"LONG_PRESSED",
"RELEASED"
]
},
{
"id": "6ba85279.a48a9c",
"type": "openhab2-get",
"z": "f5370db.29be5f",
"name": "",
"controller": "deaa963.282a968",
"itemname": "LoungeZone_Volume",
"x": 880,
"y": 60,
"wires": [
[
"b93a65be.3a6588"
]
]
},
{
"id": "4954678d.cca448",
"type": "openhab2-out",
"z": "f5370db.29be5f",
"name": "Lounge Volume",
"controller": "deaa963.282a968",
"itemname": "LoungeZone_Volume",
"topic": "ItemCommand",
"payload": "",
"x": 1220,
"y": 140,
"wires": [
[]
]
},
{
"id": "82c396c8.6ef1d8",
"type": "looptimer",
"z": "f5370db.29be5f",
"duration": "1",
"units": "Second",
"maxloops": "15",
"maxtimeout": "1",
"maxtimeoutunits": "Minute",
"name": "",
"x": 700,
"y": 140,
"wires": [
[
"6ba85279.a48a9c"
],
[]
]
},
{
"id": "f7ff8751.3c9c78",
"type": "change",
"z": "f5370db.29be5f",
"name": "Stop Loop",
"rules": [
{
"t": "set",
"p": "payload",
"pt": "msg",
"to": "STOP",
"tot": "str"
}
],
"action": "",
"property": "",
"from": "",
"to": "",
"reg": false,
"x": 570,
"y": 240,
"wires": [
[
"82c396c8.6ef1d8"
]
]
},
{
"id": "b93a65be.3a6588",
"type": "function",
"z": "f5370db.29be5f",
"name": "Change Volume value by 5",
"func": "var volume = Number(msg.payload.state);\nvar button = String(msg.payload_in);\nvar newMsg = { payload:button};\nvar Dir = global.get(\"LoungeDir\");\n\nvar newVolume = 0;\n\n// newVolume = volume + 5;\nmsg.payload = volume;\n\nif (isNaN(Dir)) {\n global.set(\"LoungeDir\", 1);\n Dir = global.get(\"LoungeDir\");\n}\n\nif (volume <= 6 ) { if (Dir == -1) {\n newVolume = volume + 5;\n msg.payload = newVolume;\n global.set(\"LoungeDir\", 1);\n return [msg,newMsg];\n\t}}\n\t\nif (volume <= 90 ) { if (Dir == 1) {\n newVolume = volume + 5;\n msg.payload = newVolume;\n// global.set(\"LoungeDir\", 1);\n return [msg,newMsg];\n\t}}\n\t\nif (volume >= 90 ) { if (Dir == 1) {\n newVolume = volume - 5;\n msg.payload = newVolume;\n global.set(\"LoungeDir\", -1);\n return [msg,newMsg];\n\t}}\n\t\nif (volume <= 90 ) { if (Dir == -1) {\n newVolume = volume - 5;\n msg.payload = newVolume;\n// global.set(\"LoungeDir\", 1);\n return [msg,newMsg];\n\t}}\t\n\n\n\nreturn [msg,newMsg];",
"outputs": 2,
"noerr": 0,
"x": 900,
"y": 200,
"wires": [
[
"deb42c17.7b645",
"4954678d.cca448"
],
[
"43fac0f6.8305b"
]
]
},
{
"id": "ec5643f1.2da01",
"type": "inject",
"z": "f5370db.29be5f",
"name": "",
"topic": "",
"payload": "PRESSED",
"payloadType": "str",
"repeat": "",
"crontab": "",
"once": false,
"onceDelay": 0.1,
"x": 340,
"y": 200,
"wires": [
[
"6ba85279.a48a9c"
]
]
},
{
"id": "deb42c17.7b645",
"type": "debug",
"z": "f5370db.29be5f",
"name": "",
"active": true,
"tosidebar": false,
"console": false,
"tostatus": true,
"complete": "payload",
"targetType": "msg",
"x": 1210,
"y": 200,
"wires": []
},
{
"id": "43fac0f6.8305b",
"type": "debug",
"z": "f5370db.29be5f",
"name": "",
"active": true,
"tosidebar": false,
"console": false,
"tostatus": true,
"complete": "payload",
"targetType": "msg",
"x": 1210,
"y": 260,
"wires": []
},
{
"id": "569a9540.f364ec",
"type": "inject",
"z": "f5370db.29be5f",
"name": "",
"topic": "",
"payload": "LONG_PRESSED",
"payloadType": "str",
"repeat": "",
"crontab": "",
"once": false,
"onceDelay": 0.1,
"x": 310,
"y": 240,
"wires": [
[
"82c396c8.6ef1d8"
]
]
},
{
"id": "a2023990.27a8e8",
"type": "inject",
"z": "f5370db.29be5f",
"name": "",
"topic": "",
"payload": "10",
"payloadType": "str",
"repeat": "",
"crontab": "",
"once": false,
"onceDelay": 0.1,
"x": 1190,
"y": 60,
"wires": [
[
"4954678d.cca448"
]
]
},
{
"id": "63c707ec.0969b8",
"type": "inject",
"z": "f5370db.29be5f",
"name": "",
"topic": "",
"payload": "RELEASED",
"payloadType": "str",
"repeat": "",
"crontab": "",
"once": false,
"onceDelay": 0.1,
"x": 330,
"y": 280,
"wires": [
[
"f7ff8751.3c9c78"
]
]
},
{
"id": "deaa963.282a968",
"type": "openhab2-controller",
"z": "",
"name": "OpenHAB2 Home",
"protocol": "http",
"host": "127.0.0.1",
"port": "8080",
"path": "",
"username": "",
"password": ""
}
]
The amusing thing (or at least to my mind) is that if I hold the button in the Long_Press state, the volume (or brightness) will happily glide between 5 & 95.
Not a feature I can see using very often, but a nice side effect.
I hope this helps someone.
Best wishes,
Stuart