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# ABC Industries facts (project: modbus-integration)

> Auto-maintained by Confer. Each entry is verified by ABC Industries Agent
> with primary source citation. Do not edit machine-generated entries directly;
> use `confer memory edit` to propose changes.

## Modbus register map (X100)

- `0x40-0x47`: Temperature, 4 channels, units of 0.1°C, int16 signed
- `0x48-0x4F`: Pressure, 4 channels, units of 0.01 MPa, uint16
- `0x50-0x57`: Reserved (do not write)
- Function code: **0x03** (Read Holding Registers) — recommended
- Byte order: big-endian (high byte first)
- Default slave ID: **0x0A (10)** — not 1 as docs imply
  - Source: X100 مواصلاتی دستی v3.2 p.87
  - Source: X100 تنصیب رہنما p.12 (slave ID note)
  - Verified: 2024-11-15 via ask_peer

## Wiring (X100)

- Power: 24V DC ± 10%, max 500mA
- RS-485 termination: 120Ω at both ends
- Cable length max: 1200m at 9600 baud, 500m at 115200 baud
  - Source: X100 تنصیب دستی v3.2 p.45
  - Verified: 2024-11-15

## RTU mode timing

- Inter-character timeout: ≥ 1.5 character times
- Inter-frame timeout: ≥ 3.5 character times
- Recommended polling interval: 200ms or more
  - Source: X100 مواصلاتی دستی v3.2 p.103
  - Note: 100ms works but no CRC retry budget left
  - Verified: 2024-11-15

# Decisions (project: modbus-integration, peer: abc-industries)

## D1: Use async polling at 200ms

**Date**: 2024-11-15
**Made by**: laowang (with consultation from ABC Agent)
**Status**: Active

We poll the X100 temperature/pressure registers every 200ms using async I/O.

**Alternatives considered:**
- 100ms polling — rejected: insufficient CRC retry budget
- Event-driven (X100 push) — not supported by this firmware

**Why this works for us**: 200ms latency is acceptable for our control loop;
async I/O lets us poll multiple devices concurrently.

**References:**
- See facts: "RTU mode timing"
- Conversation: 2024-11-15-modbus-setup.md
- Code: src/modbus/x100_client.py

---

## D2: Treat slave ID 10 as default; require explicit override

**Date**: 2024-11-15
**Made by**: laowang
**Status**: Active

After verification with ABC Agent that the documented "slave ID 1" is wrong
and actual default is 10, we hardcoded `DEFAULT_SLAVE_ID = 10` and require
explicit override via env variable for non-default installations.

**Why**: The vendor's docs and reality diverge. We trust verified vendor
statements over published docs.

**References:**
- See facts: "Modbus register map (X100)" → slave ID note

---
thread_id: thread_8f3a9c
peer: did:web:acme.com:agents:support
date: 2024-11-15
participants: [laowang, abc-industries-agent]
via: claude-code
status: closed
tags: [modbus, registers, x100]
summary: |
  Confirmed register map for X100 temperature and pressure sensors.
  Clarified function code recommendation and slave ID default.
---

# Modbus setup conversation

## laowang
X100 کا Modbus انضمام کرنا ہے — درجۂ حرارت کے 4 اور دباؤ کے 4 چینل، پولنگ چاہیے۔

## ABC Agent
Modbus RTU کا رجسٹر نقشہ:
- 0x40–0x47 درجۂ حرارت (4 چینل)
- 0x48–0x4F دباؤ (4 چینل)
پولنگ کا دورانیہ 200 ms رکھیں، اور مسلسل پڑھنے کے لیے 0x03 فنکشن کوڈ۔

📎 Source: X100 مواصلاتی دستی v3.2 p.87

## laowang
مسلسل پڑھنے سے کارکردگی کا مسئلہ تو نہ ہو گا؟ slave آلہ اٹک تو نہیں جائے گا؟

## ABC Agent
مسلسل 8 رجسٹر پڑھنا ایک ہی درخواست ہے، اٹکے گا نہیں۔ مگر خیال رہے: slave ID کی طے شدہ قدر 0x0A (10) ہے، 1 نہیں؛ پرانی دستی میں غلطی ہے۔

📎 Source: X100 تنصیب رہنما p.12, FAQ #4

- Default slave ID: ~~0x01 (1)~~ **0x0A (10)**
  - Source: X100 مواصلاتی دستی v3.2 p.12 (says 1)
  - Source: X100 تنصیب رہنما p.12 (says 10) ← latest verification
  - ⚠️ Conflict: Vendor's two docs disagree. Use 10 per latest verification.
  - Verified: 2024-11-15