ci-server-engineer/.claude/skills/data-access/tasks/opcua-client.md

---

task: OPC UA client to an OPC UA server by quick load (loopback to CI Server's own OPC UA server) version: R1.05 (first written for R1.03) source: IM 36K10L45-01EN 5th ed. (Feb. 2026) §10, §11; IM 36K10E20-01EN 4th ed. (Feb. 2026) §2; practiced on CI-Eng-Sample 2026-10-01 on R1.03 (station CIENG_UA; full remove/reload; point also configured in the Engineering Module by the user and compared) status: verified on R1.03 (§1–§6). R1.05 (2026-10-08, read-only): line/station/subscription/point dataset definitions identical to R1.03, PKI folders and client setup files checked; the loopback itself was not re-run on the shared R1.05 test server. §7 (methods) from docs.

OPC UA client to an OPC UA server

Worked example: CI-Eng-Sample station CIENG_UA, CI Server's OPC UA client reading CI-Eng-Sample.TANK1.LEVEL back through CI Server's own OPC UA server (examples/CI-Eng-Sample/12_–15_*.qli, removal 76_–78_). For a real server, replace the endpoint, security settings and node IDs.

1. Server side: make the data visible

On the CI Server OPC UA server an item is reachable only when the item has OPC visible and Read (Write to allow writing) and every parent section is OPC visible (12_opc_visible_df.qli, loaded with dssqld -m):

@FIELDS
NAME,OPC_VISIBLE

@SECTION_DF
"CI-Eng-Sample",1
"CI-Eng-Sample.TANK1",1

@FIELDS
NAME,OPC_VISIBLE,OPC_READ,OPC_WRITE

@ITEM_DF
"CI-Eng-Sample.TANK1.LEVEL",1,1,0

Visible without Read: the item shows when browsing, but browsing into it fails (UncertainNotAllNodesAvailable, client message OPXC-E-BRW_NODE; verified). By the manual, Read is also what allows reading the value. These flags also apply to the OPC DA and A&E servers.

2. Client configuration (quick load, in this order)

1. Line (OPCUAC_LINE_DF): loading it creates and starts the client process EQUIPMENT_MAN (must start with OPX, ≤ 11 characters) — wait ~10 s before the station.

   "CIENG_UA_LINE","CI-Eng-Sample OPC UA loopback line","OPXCIENG"
   

   The process reads tls\sup\<process>.sup (here opxcieng.sup), else the template epauac_eqp.sup (IM 36K10L45 5th ed. §10.11; the R1.03 manual named a non-existent opxuac.sup, ISS-084). On the R1.03 test system opxcieng.sup appeared as an exact copy of the template. R1.05 template changes (verified 2026-10-08, ISS-083): new OPXC_ENABLE_EXTENDED_FUNC (NO; YES needed for OPC UA alarms), OPXC_BASE_MODEL_CHANGE_EVENT (NO), OPXC_DISABLE_SAV_FILE (NO), OPXC_ALARM_TIME_ATTRIBUTE, hidden OPXC_CERT_EXP_PERIOD_WARN (2 months), and OPXC_SERVICE_CALL_TIME_OUT 60 s (manual: 10 s). A per-process file copied from R1.03 lacks these keywords, so their defaults apply.
2. Station (OPCUAC_STATION_DF), subscription (OPCUAC_SUBSCRIPTION_DF, name <station>:<subscription>), points (OPCUAC_POINT_DF, name <station>:<point>) — see 14_opcua_station_df.qli:
   • Station: LINE, USER_ANONYMOUS 1 (or USER_NAME/USER_PASSWORD), MSG_SECURITY_01_MODE SignAndEncrypt, MSG_SECURITY_01_POLICY Basic256Sha256, SERVER_01_ENDPOINT opc.tcp://localhost:34493, STATUS_ITEM (1 = connected; a Boolean item worked on R1.03). SERVER_01_NAME/_URI may stay empty. The R1.05 OPC Interface manual (IM 36K10E20 4th ed. §2.1.2) lists states 0–5 for this item (0 preparing, 1 connected, 2 comm error/reconnecting, 3 connect failed, 4 server shutdown received, 5 connection recreated) while IM 36K10L45 §10.9.2 still calls it Boolean; not re-tested on R1.05 (ISS-080). An Integer item shows all states.
   • Subscription: REQUESTED_PUBLISH_INTERVAL 1000.
   • Point: SUBSCRIPTION, EXTERNAL_RELATION (Input, Output, Input + Output), OPC_NAMESPACE (namespace URI, not index), OPC_NODE_ID_TYPE (STRING, NUMERIC, GUID), OPC_NODE_ID.
3. Items (ITEM_DF with STATION and POINT), e.g. CI-Eng-Sample.UA.LEVEL_COPY → CIENG_UA, LEVEL.

3. Node IDs

Target	Namespace	Type	Node ID
Value of a CI Server item (by name — survives recreating the item)	urn:Yokogawa:CI_SERVER_OPC_UA_SERVER	STRING	{"0":"Value","itnm":"<Section>.<Tag>"}
Value of a CI Server item (by namespace id)	same	STRING	{"0":"Value","nsid":"<n>"}
Server state (any OPC UA server; good connection test, 0 = Running)	http://opcfoundation.org/UA/	NUMERIC	2259

In a .qli file double the quotes inside the field: "{""0"":""Value"",""itnm"":""CI-Eng-Sample.TANK1.LEVEL""}".

Pitfalls found on the test system:

• Namespace http://www.yokogawa.com/CI_Server/ (the one the manual shows) holds only the types; with it the point is silently not monitored (ISS-032).
• In the Engineering Module's Browse path, expand the item and pick its Value node (Objects/<Section>/…/<Tag>/Value, node ID {"0":"Value","nsid":"<n>"}); verified by the user: Last value and Data type filled at once. Picking the item itself stores the object ({"nsid":"<n>"}), which has no value (status 13, never monitored) (ISS-033). For quick load prefer {"0":"Value","itnm":"<item>"}: it does not depend on nsid.
• nsid numbers change when the item is deleted and created again (e.g. sample reload).

A point that is not accepted shows REVISED_SAMPLING_INTERVAL 0 in OPCUAC_POINT_DF and the log line Can't find Point [<point>] in subscription when changed; a monitored point gets the revised interval (e.g. 1000).

Browse the server from the command line (station connected): export OPCUAC_TAG_DF with a filter; start with an empty path, then Objects:

@SELECT
'OPC_STATION_NAME = "CIENG_UA" and OPC_TAG_PATH = "Objects"'
@OPCUAC_TAG_DF

Each record shows display name, namespace URI and node ID (inside OPC_TAG_INFO). Deeper paths were not found yet on R1.03 (Objects.CI-Eng-Sample returned nothing).

R1.05: OPCUAC_TAG_DF (and OPCUAC_TAG_CMPN_DF) have two new Boolean fields, REBROWSE (ask the server again) and READ_NODE_INFO (read node attributes while browsing; switching it off is faster on slow links) (installed opcuac_tag_df.dss, verified 2026-10-08; not tried). The point form has the matching Read additional node information check box, and F5 in the expanded Browse path list rebrowses (IM 36K10E20 4th ed. §2.1.5).

Data types (IM 36K10L45 5th ed. §10.3.4, from docs): UInt32, Int64 and UInt64 map to Real (no negatives for unsigned, no decimals), DateTime/UtcTime to String in the form YYYY-MM-DDThh:mm:ss.sssZ, ExtensionObject only for EURange / EngineeringUnits, enumerations as their Int32 value; one array element per point. A value that cannot be converted is logged and the item gets status Bad.

Model change events (IM 36K10L45 5th ed. §10.5, from docs): the client reacts to the server's GeneralModelChangeEvent (node or reference added: the point is recreated; deleted: the item goes offline; external alarms are refreshed with ConditionRefresh). The coarse BaseModelChangeEvent (recreate everything) is handled only with OPXC_BASE_MODEL_CHANGE_EVENT = YES. Events within 10 s are handled once; the server must support Read and Browse.

4. Certificate exchange (first connection; the user does it)

Step	Where it shows	What the user does
1. Client rejects the server	OPXC-E-CER_NO_TRU … BadCertificateUntrusted in umhlog.log; file <thumbprint>.der in %TLS_ALLUSERS_PATH%\pki\opxuac\pkiclient\rejected	Trust it: Engineering Module OPC UA Client → Certificates → Rejected → Trusted, or move the file to …\pkiclient\trusted\certs
2. Server rejects the client	client log BadSecurityChecksFailed; file CI_SERVER_OPCUA_CLIENT_<PROCESS> [<thumbprint>].der in …\pki\opxuas\pkiserver\rejected (folder created now)	Move it to …\pki\opxuas\pkiserver\trusted\certs

PowerShell: file names with [ ] need -LiteralPath, otherwise Move-Item silently does nothing:

Move-Item -LiteralPath "<rejected folder>\<file>.der" -Destination "<trusted folder>\"

The client retries every ~35 s (OPXC_STATION_CON_TRY_INTERVAL 30 s); then OPXC-I-SRV_CONN and the status item goes to 1. Certificates and trust stay when the line is removed and loaded again (verified: reload connected within 5 s without a new exchange). For an external server, its certificate arrives the same way; the client certificate (…\pkiclient\own\certs\<host>_<PROCESS>.der) must be trusted on that server.

From R1.05 the client warns in the Historical Alarm Overview and the UMH message log before its own or the server's certificate expires (IM 36K10E20 4th ed. §2.2; lead time OPXC_CERT_EXP_PERIOD_WARN, 2 months in the installed template). The own certificates made at installation were valid for 5 years on the R1.05 test server (verified 2026-10-08).

5. Check

• itmval -g -n CI-Eng-Sample.UA.COMM_OK → 1; UA.SRV_STATE → 0 status 9; UA.LEVEL_COPY follows TANK1.LEVEL within ~1 s (verified 55, 62.5, 71, 33, 44.4).
• Client log: %TLS_LOG_PATH%\<PROCESS>.log (Successfully connected station, errors with status codes); server logs OPXUAS.log, OpxUas_Sdk.log (CreateMonitoredItems).
• Off-scan/on-scan: OPCUAC_STATION_DF ON_SCAN 0/1 with dssqld -m disconnects/reconnects.

6. Remove

Items (76_), then points, subscription, station (77_), then the line (78_, stops the client process). Reset the OPC flags only if they were not there before.

7. Calling a method on an external OPC UA server (R1.04+, from docs)

Source: IM 36K10L45 5th ed. §10.6, App. 1.3–1.4; IM 36K10E20 4th ed. §2.1.6. Not practiced. Installed on R1.05 (verified 2026-10-08): dataset OPCUAC_METHOD_CALL2_DF, loader opcuac_method_u0104, AOG displays AOG_UAC_Method_Demo, AOG_UAC_Method_Call, AOG_UAC_MethodArg_Call(2) with their symbols.

1. Class for the method object (sample Java class UAC_MTD_JBASE): attribute MTD_KEY (holds the method name) and signals MTD_TRG (0 idle/done, 1 call, 2 failed), MTD_RET (result code as text; its quality holds the numeric code), MTD_IN_ARG_0… and MTD_OUT_ARG_0… (at most 10 each, same order and types as on the server). These names are reserved in that class. Use a class with a unique name per method object (App. 1.4).
2. Method under the station (Engineering Module Methods → Add method, dataset OPCUAC_METHOD_CALL2_DF, name <station>:<method>): OPC_NAMESPACE, OPC_NODE_ID_TYPE, OPC_NODE_ID. If the server does not browse its method nodes: parent object node ID by hand (MANUAL_OBJ_OPC_NODE_ID, OBJ_OPC_NAMESPACE, OBJ_OPC_NODE_ID_TYPE, OBJ_OPC_NODE_ID) and argument types by hand (MANUAL_ARGUMENT_CONFIGURATION, ARGUMENT_IN_n_TYPE / …OUT…).
3. Point, one per method: Input + Output, namespace CIX_UAC_MTD, type STRING, node ID CIX_UAC_MTD; connect it to the object's MTD_TRG signal (Connected I/O point). Set MTD_KEY to the method name. The process area goes on MTD_TRG (the method form no longer has one). MTD_TRG shows status UPD_OFFLINE.
4. Symbol and display for the class (see the AOG demo display), then trigger from there.

Upgrade from R1.03 (App. 1.3): R1.03 methods called through dataset fields (OPCUAC_METHOD_CALL_IN_DF / …_OUT_DF, both gone in R1.05) stop working. Rebuild the class with the MTD_* members (Extended reset enabled, then reset), rebuild symbols and displays, and re-save (or copy and re-add) any method with String or Boolean input arguments.