Eurotherm 3216/3116/3200 controller
Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based
as on the wire. Word order and scaling are confirmed at the hardware-verified rung and at no rung below it.
interop-verified
Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
| point | address (0-based) | type | scale | unit |
|---|
| pv_in | 1 | I16 | 0.1 | |
| tg_sp | 2 | I16 | 0.1 | |
| man_op | 3 | I16 | 0.1 | |
| wrk_op | 4 | I16 | 0.1 | |
| wkg_sp | 5 | I16 | 0.1 | |
| proportional_band | 6 | I16 | 1 | |
| control_action | 7 | I16 | 1 | |
| integral_time | 8 | I16 | 1 | |
| derivative_time | 9 | I16 | 1 | |
| alarm_1_threshold | 13 | I16 | 0.1 | |
| alarm_2_threshold | 14 | I16 | 0.1 | |
| active_setpoint_select | 15 | I16 | 1 | |
| timer_status | 23 | I16 | 1 | |
| setpoint_1 | 24 | I16 | 0.1 | |
| setpoint_2 | 25 | I16 | 0.1 | |
| remote_sp | 26 | I16 | 0.1 | |
| calculated_error | 39 | I16 | 0.1 | |
| instrument_status | 75 | U16 | 1 | |
| load_leakage_current | 79 | I16 | 0.1 | |
| load_on_current | 80 | I16 | 0.1 | |
| instrument_mode | 199 | I16 | 1 | |
| cjc_temperature | 215 | I16 | 0.1 | |
link settings as documented (unverified): RTU; default 9600 8N?; unit ID 1; FC 06; Digital communications is optional and not available in 3116 controllers. The interface may be ordered as RS232 or RS485 (2-wire).
⚠ do not write continuously changing values to TG.SP, SP1, SP2. The memory technology used in this product has a limited (100,000) number of write cycles. — Starkest reads only; we never write a control register.
bench facts as documented (unverified)
| terminals | terminals HD, HE and HF |
| A/B polarity | A(+) and B(-) |
| termination | 220Ω termination resistor on last controller in the line |
| connector | screw terminals |
| isolation | Isolated 240Vac CAT II |
| wiring notes | RS232 or RS485 (2-wire) |
| broadcast | supported |
| protocol notes | The memory technology used in this product has a limited (100,000) number of write cycles for certain parameters like TG.SP, SP1, SP2. |
| identification notes | Comms Module Type register at 12544 |
| power | High voltage supply: 100 to 240Vac, -15%, +10%, 50/60 Hz. Low voltage supply: 24Vac/dc, -15%, +10% |
| environment | ambient temperature is within 0 and 55°C (32 - 131°F) and humidity 5 to 95% RH non condensing. |
| accuracy | CT input accuracy: ±4% of reading. |
| certifications | European Directives on Safety and EMC, EN 61010, EN 61326 |
| doc revision | Issue 2.0 Dec-04 |
| firmware applicability | software version 2 |
field reports — community-sourced, unverified (checked 2026-06-11)
- Modbus Error 0x93 (data validation failure) can occur when writing setpoint values due to scaling mismatches (Eurotherm 3216 uses 1 decimal place scaling where a register value of 100 represents 10.0°C) or writing values below the hard minimum limit (typically 0°C / 32°F). [source]
- Rapid changes to instrument mode (Auto/Manual) or Timer/Programmer operations (run/hold/reset) can cause premature EEPROM wear because these states are stored in non-volatile memory on each transition. [source]
- confirmed: Baud rates [1200, 2400, 4800, 9600, 19200] with default 9600, default unit ID 1, and Modbus RTU framing — confirmed by Eurotherm 3200 Series Engineering Manual (HA028651)
- confirmed: Digital communications is optional and not available in 3116 controllers — confirmed by Eurotherm 3200 Series Engineering Manual (HA028651)
- confirmed: Physical interface terminals HD, HE, HF for RS232 or RS485 (2-wire) with 220Ω termination resistor — confirmed by Eurotherm 3216 Engineering Manual (HA027986)
- confirmed: CT input accuracy is ±4% of reading — confirmed by Eurotherm 3216 Engineering Manual (HA027986)
- confirmed: Certifications EN 61010 and EN 61326 — confirmed by Eurotherm 3216 Engineering Manual (HA027986)
- confirmed: Control warning regarding limited (100,000) write cycles for TG.SP, SP1, SP2 — confirmed by Eurotherm 3200 Series Engineering Manual (HA028651)
- confirmed: Register map addresses (pv_in @ 1, tg_sp @ 2, man_op @ 3, wrk_op @ 4, wkg_sp @ 5, proportional_band @ 6, control_action @ 7, integral_time @ 8, derivative_time @ 9, alarm_1_threshold @ 13, alarm_2_threshold @ 14, active_setpoint_select @ 15, timer_status @ 23, setpoint_1 @ 24, setpoint_2 @ 25, remote_sp @ 26, calculated_error @ 39, instrument_status @ 75, load_leakage_current @ 79, load_on_current @ 80, instrument_mode @ 199, cjc_temperature @ 215) — confirmed by Eurotherm 3216 3208 3204 User Manual Issue 13
The trust ladder
Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.
- generated — A prompt produced it. Unproven — anyone can regenerate this.
- structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
- interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
- simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
- hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.