HART-IP Driver

Overview

The IP variant of HART (Highway Addressable Remote Transducer). It performs digital read/write on 4-20 mA industrial instruments through an IP gateway. Based on the HCF public HART-IP specification.

Item	Value
opc_type	HART
Implementation class	plantpulse.driver.protocol.hart.HARTDriver
Library	In-house Java implementation (based on HCF spec, no external library dependencies)
read	✅ (cmd 1, 3, 13)
write	✅ (cmd 6, 17, 18, 19, 22)
Security	None (the HART-IP spec itself provides no authentication/encryption)
Default port	5094 (TCP)

---

Class Structure

Class	Role
HARTDriver	Lifecycle / address parser / read·write dispatch / KeepAlive thread
HartIpHeader	13-byte HART-IP header (version, type, id, status, sequence, byteCount BE)
HartCommand	HART command PDU builder — preamble + 0x82 + 5-byte address + cmd + byteCount + data + XOR
HartChecksum	Longitudinal XOR (excluding preamble)
HartDecode	float32 BE / packed-ASCII 6-bit decoder, communication status bit interpretation

---

Wire Format

HART-IP 메시지 = 13-byte 헤더 + payload

   byte 0    Version          1
   byte 1    Message Type     0=Request 1=Response 2=Publish 3=NAK
   byte 2    Message ID       0=Session-Init 1=Session-Close 2=KeepAlive 3=PDU
   byte 3    Status / Error
   byte 4-5  Sequence (BE)
   byte 6-7  ByteCount (BE, 헤더 13 byte 포함)
   byte 8-12 Reserved (0)

PDU payload (Message ID 3) =
   Preamble(0xFF×N) + Start(0x82) + Address(5) + Command(1) + ByteCount(1) + Data(N) + XOR(1)

Handshake: connect() sends Session Init (master-type 1 byte + inactivity-close-time 4 byte BE) → receives Response. Afterwards, a background KeepAlive thread periodically sends Message ID 2.

---

OPC Registration Options

Field	Meaning	Default
opc_agent_ip / opc_agent_port	Gateway IP / port	(5094 if port is 0)
options.master-type	primary / secondary	primary
options.inactivity-ms	Session inactivity close time	600000 (10 minutes)
options.keepalive-ms	KeepAlive send interval	30000
options.connect-timeout	TCP connect timeout	5000
options.read-timeout	read SO timeout	5000

---

Tag plc_address Format

Notation	Meaning	Decoding
1 or 1:pv	cmd 1 — Read PV	float32 BE (offset 3, after the 2-byte status)
3:0 ~ 3:3 or 3:pv/sv/tv/qv	cmd 3 — PV/SV/TV/QV	4 × float32 BE (simplified model)
13 or 13:tag	cmd 13 — Tag 8 char	packed-ASCII (3 byte → 4 char)

write addresses (together with address.getValue()):

Notation	Meaning	value Format
6 / polling-address	cmd 6 — Write Polling Address	integer 0..63
17 / message	cmd 17 — Write Message	32-char packed-ASCII
18 / tag / descriptor / date	cmd 18 — Tag/Descriptor/Date	tag|desc|DD/MM/YY or per sub-field
19 / final-assembly	cmd 19 — Final Assembly Number	0..16777215
22 / long-tag	cmd 22 — Long Tag (32 byte ISO-Latin-1)	arbitrary string

---

Unsupported Areas

• WirelessHART (HART 7) burst mode, asynchronous publish reception (Message Type 2).
• Device-discovery commands such as cmd 0/cmd 50/cmd 9 — can be added.
• Short-frame addressing (other than long-frame).
• manufacturer/device-type matching in the 5-byte device address (currently zero-filled).
• Synchronous handling of keepalive responses — for simplicity, keepalive responses are ignored (can be reinforced with a separate receiver thread + seq correlation).

---

Test Coverage

test/java/plantpulse/driver/protocol/hart/

Test	Verifies
HartIpHeaderTest	13-byte header round-trip
HartChecksumTest	XOR against known vectors
HartCommandTest / HartCommandWriteTest	cmd 0/1/3/13/6/17/18/19/22 PDU build
HartDecodeTest / HartEncodeTest	float32 BE, packed-ASCII (both directions), BCD date
HARTDriverAddressTest / HARTDriverWriteTest	Address parser + write dispatch
HartSpecExtraTest	Additional spec conformance

---

References

• HART-IP spec — FieldComm Group / HART Communication Foundation (member documentation).
• Code: plantpulse-edge-driver/src/plantpulse/driver/protocol/hart/.
• In production, TCP 5094 must be exposed on the gateway (e.g. ABB AC500-eCo, Pepperl+Fuchs HART Multiplexer).