Opto22 groov EPIC processor

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

point	address (0-based)	type	scale	unit
temperature_unit_select	1024	U16	1	F or C
float_format_select	1028	U16	1
analog_output_module_0_chan_0	1030	F32BE	1
analog_output_module_0_chan_1	1032	F32BE	1
analog_output_module_0_chan_2	1034	F32BE	1
analog_output_module_0_chan_3	1036	F32BE	1
digital_counter_module_0_chan_0	512	U32BE	1
digital_counter_module_0_chan_1	514	U32BE	1
digital_counter_module_0_chan_2	516	U32BE	1
digital_counter_module_0_chan_3	518	U32BE	1
analog_input_module_0_chan_0	4608	F32BE	1
analog_input_module_0_chan_1	4610	F32BE	1
analog_input_module_0_chan_2	4612	F32BE	1
analog_input_module_0_chan_3	4614	F32BE	1

link settings as documented (unverified): TCP; unit ID 1; FC 01,02,03,04,05,06,15,16,17; Modbus/TCP default port is 502. Supports up to 8 connections from Modbus masters (requires firmware R9.4B or higher for SNAP, R1.2a or higher for E1/E2).

⚠ CAUTION: If you use PAC Control, be careful that Modbus writes to I/O channels don't conflict with strategy logic. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

max registers/read	127
protocol notes	Modbus checksum is not used; instead, the Ethernet TCP/IP link layer checksum guarantees data. Packet size is limited to 256 bytes.
identification notes	Function code 0x11 (Report Slave ID) returns hardware, firmware, and loader versions.
FC 43 device ID	not supported
doc revision	Form 1678-250827—August 2025
firmware applicability	SNAP Ethernet-based controllers require firmware R9.4B or higher. E1 and E2 require firmware R1.2a.

⚠ disputed: temperature_unit_select @ 1024, float_format_select @ 1028, analog_output_module_0_chan_0 @ 1030 — disputed by Form 1678, which maps 1025 to Set Degrees in F or C, 1026 to Store Configuration to Flash, 1028 to Clear Channel Configuration, and 1030 to Hardware Reset

field reports — community-sourced, unverified (checked 2026-06-11)

Modbus/TCP function Report Slave ID (0x11) does not return any data on SNAP PAC controllers running firmware R9.4c and lower. It returns a length of 0 instead of the expected 16-byte response. Fixed in firmware R9.5a. [source]
confirmed: Modbus/TCP default port is 502. Supports up to 8 connections from Modbus masters (requires firmware R9.4B or higher for SNAP, R1.2a or higher for E1/E2) — confirmed by Opto 22 Modbus/TCP Protocol Guide (Form 1678)
confirmed: Modbus checksum is not used; instead, the Ethernet TCP/IP link layer checksum guarantees data. Packet size is limited to 256 bytes — confirmed by Opto 22 Modbus/TCP Protocol Guide (Form 1678)
confirmed: Form 1678-250827—August 2025 — confirmed by Opto 22 document catalog
confirmed: CAUTION: If you use PAC Control, be careful that Modbus writes to I/O channels don't conflict with strategy logic — confirmed by Opto 22 Modbus/TCP Protocol Guide (Form 1678)

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.
coherence-checked — Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

Device not here? Upload its manual and get a checked map back. It's free.

Want it confirmed against your own device? Order hardware verification. If it doesn't check out, you don't pay.

Building on a lot of devices? License the library — machine-readable maps, the firmware matrix, and API access.