Module configuration 

Configuration

Runtime environment variables

ExecutorConfig::from_env() reads these at startup:

Variable	Description	Default
ROS_DOMAIN_ID	ROS 2 domain ID	0
NROS_LOCATOR	Router address (tcp/…, udp/…, or tls/…)	tcp/127.0.0.1:7447
NROS_SESSION_MODE	Session mode: client or peer	client
ZENOH_TLS_ROOT_CA_CERTIFICATE	Path to CA certificate (PEM)	—
ZENOH_TLS_ROOT_CA_CERTIFICATE_BASE64	Base64-encoded CA cert (bare-metal)	—

Buffer tuning (build-time)

Set these environment variables before cargo build. After changing a value, run cargo clean -p zpico-sys (or xrce-sys) to force a rebuild.

Zenoh backend (ZPICO_*):

Variable	Description	Posix	Embedded
NROS_ZENOH_FRAG_MAX_SIZE	Max reassembled message size	65536	2048
NROS_ZENOH_BATCH_UNICAST_SIZE	Max unicast batch before fragmentation	65536	1024
NROS_ZENOH_BATCH_MULTICAST_SIZE	Max multicast batch size	8192	1024
NROS_SUBSCRIBER_BUFFER_SIZE	Per-subscriber buffer in zenoh shim	1024	1024
NROS_SERVICE_INBOX_BYTES	Request slot of a user service server’s inbox ring (zenoh); ZPICO_SERVICE_BUFFER_SIZE is its one-release alias	1024	1024
NROS_SERVICE_INBOX_DEPTH	Requests a user service server holds before dropping the newest	4	4
NROS_ACTION_INBOX_BYTES	Request slot of an action server queryable’s inbox ring	NROS_SERVICE_INBOX_BYTES	ditto
NROS_ACTION_INBOX_DEPTH	Requests an action server queryable holds (the twin of ZPICO_MAX_PENDING_REPLIES)	4	4

XRCE-DDS backend (XRCE_*):

Variable	Description	Posix	Embedded
XRCE_TRANSPORT_MTU	Transport MTU (also sizes stream buffers)	4096	512
XRCE_BUFFER_SIZE	Default of the three receive families below	1024	1024
XRCE_SUBSCRIBER_BUFFER_SIZE	Subscriber ring entry	XRCE_BUFFER_SIZE	ditto
XRCE_SERVICE_REQUEST_BUFFER_SIZE	Service-server request entry	XRCE_BUFFER_SIZE	ditto
XRCE_SERVICE_REPLY_BUFFER_SIZE	Service-client reply slot	XRCE_BUFFER_SIZE	ditto
XRCE_STREAM_HISTORY	Reliable stream history depth (>= 2)	4	4

The zenoh service inbox is per FAMILY since phase-461 W1 (issue 1352): a user service and an action server queryable each take a slot size and a ring depth of their own, and the parameter and lifecycle services bring their own ring, sized by nros-node from the contract’s declared parameters. An image that states nothing gets the one table it had.

The three families were one number until phase-454 W6.b, so a subscriber ring entry paid for the largest type a SERVICE carried, 32 x 8 times over. Two of them are also DERIVED from what the image declares when it declares it (RFC-0100): the subscriber entry takes the largest wire bound over the declared subscriptions and XRCE_STREAM_HISTORY drops to the protocol floor of 4 when no endpoint declares reliability = reliable. Stating either here still wins.

Core (NROS_*, C API only):

Variable	Description	Default
NROS_MAX_PARAMETERS	Max parameters in parameter server	32

Example — increase zenoh defrag to 128 KB for large point clouds:

NROS_ZENOH_FRAG_MAX_SIZE=131072 cargo build --features rmw-zenoh,platform-posix