LMSDeviceModule

Crestron SIMPL+ module for controlling Lyrion Music Server (LMS) via HTTP JSON-RPC on a CP4N processor.

Drop-in replacement for RoonDeviceModule v1.0 Build 10 — same signal layout, same panel wiring.

Features

• Play, Pause, Stop, Next, Previous track
• Volume control (absolute, normalized, up/down, mute/unmute)
• Shuffle and Repeat (loop, loop one) toggle
• Seek (absolute and normalized)
• Now Playing feedback: title, artist, album, artwork URL
• Track position and duration with formatted time strings
• Player auto-discovery by name

Architecture

The module does not use SIMPL+ TCP sockets (which silently fail on 4-series). Instead:

1. A Generic TCP/IP Client symbol in SIMPL Windows handles TCP transport
2. The SIMPL+ module formats HTTP JSON-RPC requests and parses responses via serial I/O
3. STRING_INPUT (not BUFFER_INPUT) is used for RX to avoid CIP auto-reconnect buffer accumulation issues
4. Polls LMS every 5 seconds using WHILE(1) { DELAY(500); } in Main()

Each poll cycle: Connect -> Send HTTP POST -> Receive response -> Parse via Content-Length -> Disconnect.

Setup

Parameters

Parameter	Description	Example
LMS_IP	IP address of your LMS server	192.168.1.180
DefaultPlayer	Player name to control	Music Room

SIMPL Windows Wiring

Add a Generic TCP/IP Client symbol and wire it to the module:

TCP/IP Client Signal	Module Signal	Direction
TCP_Connect (Connect)	TCP_Connect	Output from module
TCP_Connected (Connected)	TCP_Connected	Input to module
TCP_Disconnect (Disconnect)	TCP_Disconnect	Output from module
To_Device (TX)	To_Device	Output from module
From_Device (RX)	From_Device	Input to module

Set the TCP/IP Client's port to 9000 and address to your LMS server IP.

Signal Layout

The module's digital/analog/serial I/O matches RoonDeviceModule v1.0 Build 10 pin-for-pin, so existing panel smart objects and SIMPL logic work without changes.

LMS JSON-RPC

The module communicates via HTTP POST to /jsonrpc.js:

{
  "id": 1,
  "method": "slim.request",
  "params": ["<playerid>", ["<command>", "<args>"]]
}

Player discovery uses ["players", 0, 10]. Status polling uses ["status", "-", 1, "tags:cgaldK"].

Key Lessons Learned

• STRING_INPUT not BUFFER_INPUT for TCP RX: BUFFER_INPUT has a hidden internal buffer that accumulates data uncontrollably with CIP auto-reconnect. STRING_INPUT delivers one chunk per CHANGE event with no hidden state.
• CIP auto-reconnect: The Generic TCP/IP Client auto-reconnects when Connect=1 and the server closes the connection. TCP_Connect = 0 set in a CHANGE handler doesn't propagate fast enough to prevent it.
• Connection: close: LMS echoes this header back only if the client sends it. Without it, LMS keeps the connection alive.
• SIMPL+ named WAITs: Must be defined lexically before any CANCELWAIT/RETIMEWAIT references. WHILE+DELAY in Main() is simpler and more reliable for polling.
• progreset does not reset CIP sockets: If the socket enters a corrupted state (ObjectDisposedException), a full processor reboot is required.

License

MIT