HDMI Matrix and Display Control with KNX: RS-232 Switching and Meeting Room AV Scenes

Kramer VS-44DT RS-232 command set (4×4 HDBT matrix)

RS-232 settings: 9600 baud, 8N1, no hardware flow control

Route input to output (Kramer Protocol 3000):
  #ROUTE 1,<output>,<input>CR
  Example: #ROUTE 1,1,2CR   → Output 1 = Input 2 (laptop)
  Example: #ROUTE 1,1,1CR   → Output 1 = Input 1 (PC)
  Example: #ROUTE 1,2,3CR   → Output 2 = Input 3 (Blu-ray)

Route all outputs to same input:
  #ROUTE 1,0,<input>CR      → 0 = all outputs
  Example: #ROUTE 1,0,1CR   → all outputs = Input 1

Mute video output:
  #VMUTE 1,<output>,1CR     → mute output
  #VMUTE 1,<output>,0CR     → unmute output

Power on/off (if matrix has standby):
  #POWER 1CR                → power on
  #POWER 0CR                → standby

Response to valid command:
  ~01@ROUTE 1,1,2OK         → acknowledgement
  Timeout if no response: check RS-232 wiring and baud rate

Extron SW4 HDMI command set (4:1 switcher)

RS-232 settings: 9600 baud, 8N1, no hardware flow control
(Extron SIS — Simple Instruction Set)

Select input (SIS command):
  <input_number>!CR         → select input
  Example: 1!CR → Input 1
  Example: 2!CR → Input 2
  Example: 3!CR → Input 3

No response on success (Extron SIS is one-way for basic commands)
Query current input:
  I CR                      → returns current input number

Video mute:
  1B CR                     → video mute ON
  0B CR                     → video mute OFF

Note: Extron VS and SMX series matrices use a different
command set (SIS+ or XTP protocol) — verify model manual
before writing control commands

iTach Flex RS-232 wiring and configuration

Hardware wiring:
  GlobalCache iTach Flex → RS-232 module (GC-100-01R)
  DB9 Male connector:
    Pin 2 (RX) → Matrix/Display TX
    Pin 3 (TX) → Matrix/Display RX
    Pin 5 (GND) → Matrix/Display GND
  3-wire RS-232 (no hardware flow control required for Kramer/Extron)

iTach Flex network configuration (iHelp app):
  DHCP: OFF → assign static IP (e.g. 192.168.1.200)
  Module: Serial (RS-232)
  Baud rate: 9600 (match matrix setting)
  Data bits: 8, Parity: None, Stop bits: 1
  Flow control: None

TCP send port: 4999 (default, all GlobalCache devices)
TCP connection: persistent (do not close between commands)

Test command via netcat (Linux/Mac):
  echo -e "#ROUTE 1,1,2
" | nc 192.168.1.200 4999
  → Matrix should route Input 2 to Output 1
  → Monitor iTach LED: blinks on TX/RX activity

Display RS-232 power commands

Samsung Commercial (MDC protocol):
  RS-232: 9600 8N1
  Power ON:  0xAA 0x11 0x01 0x01 0x01 0x14 (hex bytes)
  Power OFF: 0xAA 0x11 0x01 0x01 0x00 0x13
  Input HDMI1: 0xAA 0x14 0x01 0x01 0x21 0x37

NEC Large Format Displays:
  RS-232: 9600 8N1
  Power ON:  0x01 0x30 0x41 0x30 0x41 0x30 0x43 0x02 0x43 0x32 0x30 0x33 0x44 0x36 0x30 0x31 0x03 0x73 0x0D
             (NEC control command for power = ON)
  Power OFF: similar structure, parameter 0x34

LG Commercial (RS-232C protocol):
  RS-232: 9600 8N1, CR terminated
  Power ON:  ka 01 01
  Power OFF: ka 01 00
  Input HDMI: xb 01 90
 (HDMI1)

HDMI CEC (via matrix CEC pass-through):
  Kramer VS-44DT: CEC pass-through ON by default
  TV on: CEC command 0x04 (Image View On) + 0x82 (Set Active Source)
  TV off: CEC command 0x36 (Standby) broadcast
  CEC control via iTach or dedicated CEC controller (Pulse-Eight USB-CEC)

KNX scene GA 7/2/0 (DPT 18.001) — meeting room AV scenes

Scene 1 — "Meeting" (value 0):
  HDMI: #ROUTE 1,1,1CR → Output 1 (display) = Input 1 (room PC)
  Display: power ON (RS-232 or CEC)
  DALI: recall scene 3 (60%, 4000K collaborative)
  Audio (if DSP): recall "Conference Mode" preset

Scene 2 — "Presentation" (value 1):
  HDMI: #ROUTE 1,1,2CR → Output 1 = Input 2 (laptop HDMI)
        #ROUTE 1,2,2CR → Output 2 (overflow display) = Input 2
  Display 1+2: power ON
  DALI: recall scene 4 (30%, 3000K — dim for projector viewing)
  Audio: recall "Presentation Mode" preset

Scene 0 — "Off" (value 63 per DPT 18.001):
  HDMI: #VMUTE 1,0,1CR → mute all outputs (video blank)
  Display 1+2: power OFF (RS-232 or CEC standby)
  DALI: recall scene 0 (all off, with 5-min ramp-down)
  Audio: recall "Standby" preset (all muted)

KNX implementation:
  Middleware monitors GA 7/2/0
  On value 0: sends "Meeting" RS-232 commands to iTach
  On value 1: sends "Presentation" RS-232 commands
  On value 63: sends all-off commands + display off

PuTTY RS-232 commissioning procedure

Step 1: Direct RS-232 test (laptop → matrix):
  USB-to-RS-232 adapter → DB9 cable → matrix RS-232 port
  PuTTY: Connection type = Serial
  Serial line: COM3 (or /dev/ttyUSB0 on Linux)
  Speed: 9600, Data: 8, Stop: 1, Parity: None, Flow: None
  Open terminal

  Type: #ROUTE 1,1,1 then press Ctrl+M (sends CR)
  → Display connected to Output 1 should show Input 1 content
  → PuTTY: response ~01@ROUTE 1,1,1OK should appear

  Type: #ROUTE 1,1,2 then Ctrl+M
  → Display should switch to Input 2

Step 2: iTach bridge test:
  Connect iTach RS-232 module to matrix (3-wire)
  netcat test: echo -e "#ROUTE 1,1,1
" | nc <iTach-IP> 4999
  → Verify same switching as direct RS-232 test

Step 3: KNX scene test (end-to-end):
  Write value 0 to GA 7/2/0 (Scene 1 = Meeting)
  → Middleware log: RS-232 commands sent to iTach
  → HDMI matrix: Output 1 switches to Input 1
  → Display: powers on
  → DALI: scene 3 activates (60% 4000K)

  Write value 63 to GA 7/2/0 (Scene 0 = Off)
  → All displays power off, DALI scene 0 (off)

Step 4: Verify display power via RS-232:
  Direct RS-232 test Samsung MDC power ON command (hex bytes)
  → Display screen activates → command verified
  Then through iTach with hex byte command via netcat