Limits and defaults

The numbers the gateway enforces or starts with, grouped by area. A default can be changed where the table says; a limit cannot. Durations in configuration keys are .NET TimeSpan strings (d.hh:mm:ss).

Live data (/sync)

Item	Value	Notes
Sockets per user	32	Limit
Subscriptions per socket	10,000	Limit
Socket closed after its session ends	within 30 s	Also when the session no longer holds a known role
Slow client	Oldest queued frames dropped; a client too far behind is disconnected
WebSocket keep-alive	ping every 30 s, timeout 60 s

See Sync.

Replay

Item	Value	Notes
Replays at once, gateway-wide	8	Limit; one per socket, a second request ends the first
Gap shortening	Gaps over 5 s play as 5 s
Checkpoint interval	1 hour	EventBackbone__CheckpointInterval, a whole fraction of an hour
Checkpoint retention	value retention + 2 hours
Checkpoint lookback at start	up to 6 hours back; with none, the last hour of values is folded in
replay.status while playing	about 4 per second
Alarm history available to a replay	Alarms__EventRetention (365 days)	Further back shows no alarms

See History and replay.

Event backbone

Item	Default	Key
Value retention	7 days	EventBackbone__ValueRetention
Metadata retention	30 days	EventBackbone__MetadataRetention
Batch size	256 values	EventBackbone__BatchMaxCount
Batch latency	25 ms	EventBackbone__BatchMaxLatencyMs
tag.replay from the backbone	at most 10,000 stored batches read from the start of a range (truncated)	Limit
History module answer timeout	15 s, then the backbone answers	Limit
SQLite checkpoint	every 5 s	WAL mode, synchronous=NORMAL

See Configuration.

Scripts

Script kind	Statements	Memory	CPU time
Expression tag	50,000	16 MiB	250 ms
Screen script	500,000	32 MiB	2 s
Module script (cron)	2,000,000	32 MiB	5 s

Item	Value
Source length	64 KiB
A script's tag reads, in all	5 s
Worker pool	2 ready from start, up to 4 on a machine with the cores, about 50 to 60 MiB each
Worker heap	256 MiB; running out ends that worker
Stuck script	killed 1 s after its limit
Refusal after a crash	5 s, doubling each time up to 5 min
Module scripts	one at a time across the gateway

See Scripting.

Alarms

Item	Value	Notes
Severity	1 to 1000, default 500
On-delay	up to one day (onDelayMs)	On the gateway's clock
Evaluation queue	32,768 values	In memory; a burst past it is not evaluated, the state converges on the newest value
Renames, tag disables and deletes picked up	within 5 s
History retention	365 days	Alarms__EventRetention

See Alarms.

Alarm pipelines and event streams

Item	Value
Pipeline deliveries kept in the log	last 500
Pipeline webhook timeout	10 s
Event stream batches kept in memory (log)	last 200
Event stream batches held for resending when the receiver is down	up to 50 per stream, resent every 10 s, oldest first; lost on restart
Event stream webhook timeout	10 s
Response detail kept	300 characters

See Alarm pipelines and Event streams.

Historian and cron

Item	Value	Notes
Historian retention	90 days default, up to 36,500	retentionDays on the historian's settings; shortening prunes at once, otherwise hourly
Cron runs kept	90 days, at most 2,000 per job
Cron schedule	five fields, per-job time zone; nothing below a minute

See Historian and Cron.

Modules

Item	Value	Notes
Upload size	200 MB	Limit, 400 when exceeded
Files in a package	5,000	Limit
Unpacked size	400 MB	Limit
Stop timeout	30 s	Modules__StopTimeoutSeconds
Start timeout	120 s	Modules__StartTimeoutSeconds
Log lines in memory, per module	2,000
Log files, per module	5 of 2 MB each	Modules__LogFileBytes
Log stream keepalive	every 15 s	Server-sent events
Default log level	information	Changeable at run time

See Modules.

Tags and tag types

Item	Value
Type inheritance depth	8 types
Derived bit number	0 to 63
@gateway.performance.* publish interval	every 10 s
@gateway.time	once a second
Connection state gathered for @gateway.connection tags	every 2 s

See Tags and Tag types.

Security and audit

Item	Value	Notes
Session lifetime	7 days from sign-in	Not sliding; cookie scadex.session
Write audit value	cut to 4 KB	Nothing prunes the table yet
Gateway log buffer	newest 2,000 lines	In memory, not persisted
Screen presence heartbeat	every 15 s, expires after 45 s	Who has a screen open in the editor

See Security and Audit log.