NervesGate.
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CAN and RS485 ownership, SDK access and bounded diagnostics on allowlisted ports.
SDK serial claims exclude diagnostics and are released on owner exit. CAN receive sockets are shared by process-owned subscriptions. SDK sends never configure an interface or leave listen-only mode.
Commands
configure/3, capture/2 and modbus_read/3 return :ok when accepted,
or {:error, reason}. CAN configuration and diagnostics complete asynchronously;
RS485 configuration changes its in-memory opt-in immediately. Only one worker
runs at a time. Read status/1 for completion, errors and results.
Queries and notifications
status/1 returns detected ports, the current operation and the last result.
observe/1 subscribes the caller to changes. Idle observations never open UARTs
or transmit traffic. Serial opt-in and results reset on restart.
The optional server argument defaults to this module.
:bus_port_unavailable reports a missing, known enabled port. CAN enablement
comes from observations; RS485 from explicit opt-in. Missing observations never
erase known enablement. An observed return or removal of opt-in clears the
condition. After restart, unknown CAN state preserves the previous alarm.
Summary
Functions
Start receive-only capture on an enabled port: up to five seconds, 200 frames or 4096 bytes.
Returns a specification to start this module under a supervisor.
Configure can0/can1 or opt ttyS3/ttyS4 in or out of diagnostics.
Request one authorized Modbus RTU read on ttyS3/ttyS4, without retry.
Subscribe the caller to bus status/result hints; reread status on notification.
Read ports, operation, result and error. An accepted operation finishes when operation is nil.
Functions
@spec capture(String.t(), GenServer.server()) :: :ok | {:error, term()}
Start receive-only capture on an enabled port: up to five seconds, 200 frames or 4096 bytes.
Returns a specification to start this module under a supervisor.
See Supervisor.
@spec configure(String.t(), map(), GenServer.server()) :: :ok | {:error, term()}
Configure can0/can1 or opt ttyS3/ttyS4 in or out of diagnostics.
Params use string keys: "enabled" is required; CAN also requires a supported
"bitrate" and defaults to listen-only mode. Administrators can explicitly set
"listen_only" => false to permit SDK transmission; passive diagnostics still
require listen-only mode. RS485 uses fixed 9600 8N1.
@spec modbus_read(String.t(), map(), GenServer.server()) :: :ok | {:error, term()}
Request one authorized Modbus RTU read on ttyS3/ttyS4, without retry.
String-keyed params: "authorized" must be true, "unit" 1–247,
"function" 3 or 4, "address" zero-based 0–65535, and "count" 1–32
without crossing address 65535. The operator must ensure no other master is active.
@spec observe(GenServer.server()) :: :ok | {:error, :unavailable}
Subscribe the caller to bus status/result hints; reread status on notification.
@spec status(GenServer.server()) :: map()
Read ports, operation, result and error. An accepted operation finishes when operation is nil.