OPC-UA Driver

Overview

Industrial data standard protocol based on OPC Unified Architecture (IEC 62541).

Item	Value
opc_type	OPCUA
Implementation Class	plantpulse.driver.protocol.opcua.OPCUA_34_Driver
Library	Eclipse Milo (milo-sdk-client)
read	✅
write	✅ (node.writeValue)
Security	User Authentication Anonymous, Username/Password. Channel Security None · Sign · SignAndEncrypt · auto

Compatible with most OPC-UA servers, including Kepware, Matrikon, and Prosys.

---

OPC Registration Form

Field	Meaning	Example
opc_agent_ip	OPC-UA Server IP	192.168.0.40
opc_agent_port	OPC-UA Server TCP Port	49320 (Kepware default)
timecycle	Polling Cycle (ms)	1000
options.servername	Server Name at the end of endpoint	(Leave blank for Kepware)
options.username	Authentication User	kopens
options.password	Authentication Password	***
options.discovery	If true, browse the entire node tree from RootFolder during connection and log it (Not endpoint discovery — use [Endpoint Lookup] on screen for endpoints)	false (Recommended)
options.security_mode	Channel security mode. None (Default) · Sign · SignAndEncrypt · auto (Strongest among Sign·SignAndEncrypt). If not None, it will not downgrade to None. Case-insensitive; unknown values become OPCUA_SECURITY_CONFIG_INVALID	SignAndEncrypt
options.security_policy	auto (Default) · Basic256Sha256 · Aes128_Sha256_RsaOaep · Aes256_Sha256_RsaPss. auto follows the order Aes256_Sha256_RsaPss > Basic256Sha256 > Aes128_Sha256_RsaOaep. Ignored if security mode is None	auto
options.allow_deprecated_policy	If true, allow deprecated Basic256 · Basic128Rsa15 (Included in auto candidates and can be specified). Values other than true/false become OPCUA_SECURITY_CONFIG_INVALID	false

Generated endpoint URL format:

opc.tcp://<opc_agent_ip>:<opc_agent_port>/<servername>

If both username + password exist, use UsernameProvider; otherwise, use AnonymousProvider.

pki_dir (Client certificate and trust list directory) is not an input field. edge-web inserts $PE_DATA_DIR/pp-data/opcua-client only when the security mode is not None, and values stored in the connection row are discarded.

Endpoint Selection:

• security_mode=None (OPCUA_34_Driver.selectEndpoint) — Selects only those that are MessageSecurityMode.None from the list advertised by the server. The endpoint that advertises the token type to be used (UserName / Anonymous) takes priority; otherwise, the first None endpoint is selected.
• Other modes (OpcuaEndpointSelector.selectSecure) — Selects the strongest endpoint that satisfies both the accepting mode/policy and the token type to be used. If none exist, it does not downgrade to None and fails with OPCUA_NO_MATCHING_ENDPOINT.

The host of the selected endpoint URL is replaced by opc_agent_ip (Ports and paths are values advertised by the server). Failures with known causes (Certificate · Security Setting · No Matching Endpoint) leave a single line of OPCUA connect refused: error_code=<코드> opc_id=<OPC ID> ... WARN (only once for the same cause). OPCUA_CONNECT_FAILED · OPCUA_PKI_ERROR leave OPCUA connect failed: ... ERROR and a stack trace every time.

Screen Procedure for Secure Connection

Refer to OPC-UA Connection — Secure Connection for server certificate trust, downloading edge certificates, and error messages. First-time server certificates are rejected (no automatic trust on first connection) and are connected after the operator trusts them on the screen.

---

Tag plc_address Format

Standard OPC-UA NodeId notation. Example:

Notation	Meaning
ns=2;s=Simulator.Sine1	namespace 2, string identifier Simulator.Sine1
ns=2;i=1234	numeric identifier 1234
ns=3;g=09087e75-8e5e-499b-954f-f2a8624db28a	GUID identifier
ns=2;b=Mb=	opaque (bytestring) identifier

For Kepware, usually in ns=2;s=<Channel>.<Device>.<Tag> format.

---

data_type / format Mapping

Returns the Value of the OPC-UA variable node after casting it to a String. data_type is used for casting in subsequent stages (PLCValueFomula, Sparkplug publishing, etc.).

data_type	Operation
Float / Double	Number as-is
Int / Integer / Int32 / Short / Long	Number as-is
Boolean / Bool	true/false string
String / Text	UTF-8 string
DateTime	ISO string

format is generally not used in OPC-UA. Use fomula if post-processing formulas are required.

---

Common Errors + Troubleshooting

Message / Symptom	Cause	Resolution
connection refused	Server not running, port blocked	Verify communication via telnet <ip> <port>
Bad_UserAccessDenied	Username/password error, anonymous not allowed	Register user on server or enable anonymous
OPCUA_CLIENT_CERT_REJECTED (Bad_SecurityChecksFailed etc.)	Server does not trust the edge client certificate	Add edge certificate (.der) to server trust list
OPCUA_NO_MATCHING_ENDPOINT	Server does not advertise an endpoint with that mode/policy/token	Verify available combinations via [Endpoint Lookup] on screen and match
Connection failure due to incorrect port	Driver replaces only the host of the advertised endpoint with opc_agent_ip; ports/paths are used as-is	If port is exposed via NAT/port forwarding, match it to the port advertised by the server. No hosts mapping required
Value is always 0 / null	NodeId typo, namespace number mismatch	Verify NodeId read using clients like UA Expert

---

curl Registration Example

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_UA_Kepware",
    "opc_type": "OPCUA",
    "opc_name": "Kepware",
    "opc_agent_ip": "192.168.0.40",
    "opc_agent_port": "49320",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": {
      "username": "kopens",
      "password": "***",
      "discovery": "false"
    },
    "tag_list": [
      {
        "tag_id": "OPC_UA_Kepware_TAG_00001",
        "tag_name": "Sine1",
        "plc_address": "ns=2;s=Simulator.Sine1",
        "data_type": "Float",
        "description": "Sine wave"
      },
      {
        "tag_id": "OPC_UA_Kepware_TAG_00002",
        "tag_name": "Random1",
        "plc_address": "ns=2;s=Simulator.Random1",
        "data_type": "Integer"
      }
    ]
  }'

Read value:

curl -s http://<edge-host>/api/v1/tag/OPC_UA_Kepware_TAG_00001/value | jq

---

Reference: Kepware Quick Setup Guide

1. Kepware Server → Project → Add Channel (e.g., Simulator).
2. Add Device (e.g., Simulator) → Model = 16 Bit Device.
3. Add Tags → Sine1, type Float, scan rate 100ms, etc.
4. Enable port 49320 in Project Properties → OPC UA → Server Endpoint.
5. Enable Anonymous or user account. For secure connections, enable Sign and Encrypt with Basic256Sha256 or higher in the endpoint security policy and add the edge certificate to the trust list.

→ Edge Registration Form:

Field	Value
opc_agent_ip	Kepware Server IP
opc_agent_port	49320
options.servername	(Leave blank)
options.username/password	Account created above
plc_address	ns=2;s=Simulator.Simulator.Sine1

---

Example Collection (by Data Type)

OPC-UA returns the value (Variant) of the variable node after casting it to a String. data_type is used for casting during post-processing (PLCValueFomula, Sparkplug DataTypeMapper). format is generally not used.

Boolean

data_type	plc_address Example	Note
Boolean	ns=2;s=Simulator.Boolean1	Kepware Simulator Boolean tag
Boolean	ns=2;s=PLC.Status.Running	Kepware Channel.Device.Tag
Boolean	ns=2;i=1003	numeric NodeId

16/32-bit Integer

data_type	plc_address Example	Note
Integer	ns=2;s=Simulator.Random1	Random integer simulation
Integer	ns=2;s=Simulator.Counter1	Counter
Integer	ns=2;s=PLC.D100	Kepware MELSEC channel exposure

64-bit Integer

data_type	plc_address Example	Note
Long	ns=2;s=Simulator.LongCounter	UInt64 / Int64 node
Long	ns=2;s=PLC.Cycle.Total	Cumulative counter

Floating Point

data_type	plc_address Example	Note
Float	ns=2;s=Simulator.Sine1	sine wave simulation
Float	ns=2;s=Simulator.Ramp1	ramp wave
Double	ns=2;s=PLC.Pressure	Precision measurement value

String

data_type	plc_address Example	Note
String	ns=2;s=Simulator.User1.Name	String node
String	ns=2;s=PLC.Recipe.Active	Recipe name

By NodeId Format

identifier type	plc_address Example
String (s=)	ns=2;s=Simulator.Sine1
Numeric (i=)	ns=2;i=1234
GUID (g=)	ns=3;g=09087e75-8e5e-499b-954f-f2a8624db28a
Opaque (b=)	ns=2;b=Mb=

Formula Utilization

Usage	data_type	fomula	Note
Unit Conversion	Float	${VALUE}*0.001	g → kg, etc.
Zero Point Calibration	Float	${VALUE}-${TAG_ZERO}	Other OPCUA tags can be referenced
Type Conversion	Float	${VALUE}*1.0	Force Integer → Float
Polynomial	Float	${VALUE}*${VALUE}*0.0001	Non-linear

Comprehensive curl Example (All Types)

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_UA_FULL",
    "opc_type": "OPCUA",
    "opc_name": "Kepware Full",
    "opc_agent_ip": "192.168.0.40",
    "opc_agent_port": "49320",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": { "discovery": "false" },
    "tag_list": [
      {"tag_id":"OPC_UA_FULL_T01", "tag_name":"BoolTag",    "plc_address":"ns=2;s=Simulator.Boolean1",        "data_type":"Boolean"},
      {"tag_id":"OPC_UA_FULL_T02", "tag_name":"IntTag",     "plc_address":"ns=2;s=Simulator.Random1",         "data_type":"Integer"},
      {"tag_id":"OPC_UA_FULL_T03", "tag_name":"LongTag",    "plc_address":"ns=2;s=Simulator.LongCounter",     "data_type":"Long"},
      {"tag_id":"OPC_UA_FULL_T04", "tag_name":"FloatTag",   "plc_address":"ns=2;s=Simulator.Sine1",           "data_type":"Float"},
      {"tag_id":"OPC_UA_FULL_T05", "tag_name":"DoubleTag",  "plc_address":"ns=2;s=PLC.Pressure",              "data_type":"Double"},
      {"tag_id":"OPC_UA_FULL_T06", "tag_name":"StringTag",  "plc_address":"ns=2;s=Simulator.User1.Name",      "data_type":"String"},
      {"tag_id":"OPC_UA_FULL_T07", "tag_name":"NumIdTag",   "plc_address":"ns=2;i=1234",                       "data_type":"Integer"},
      {"tag_id":"OPC_UA_FULL_T08", "tag_name":"ScaledTag",  "plc_address":"ns=2;s=Simulator.Sine1",           "data_type":"Float", "fomula":"${VALUE}*100"}
    ]
  }'