CTS 602 controller with HMI350T control panel Modbus register map

Notes

Source: Nilan 'Protocol description – CTS602 with HMI350T, Modbus version 23', document 52173104, revision 22.11.2023: section 3 'Setup' (node address default 30, 19200 bps, 8 data bits, 1 stop bit, even parity, communication speed and framing cannot be changed) and section 5 'Register layout' (5.1 input registers, 5.2 holding registers). The CTS 602 is an RS-485 Modbus RTU slave, so it is reached through a Modbus RTU-to-TCP gateway using the factory serial settings above. The manual's own note states that its tables list 'the register addresses as used in Modbus messages without the global offset' (reading input register 100 with function code 04 gives global address 30101), so the numbers here are wire addresses and the seed declares zero-based addressing. Only input registers are listed: the manual publishes name, address, scale and unit but no per-register write access for the holding-register block, and the app has to know whether a row may be written, so the holding registers are left out rather than guessed. Temperature rows are signed 16-bit: the same document documents temperature ranges such as '-40.00 °C - 99.00 °C'. The registers with a 100 scale are entered with 0.01. Three groups are left out for the same reason: the version/ID text registers 003-005 and 100 (the 'text' flag in the scale column cannot be tied to a single row because the description column is a stacked block), the pressure rows 219/220 (bar, no scale published) and the humidity/CO2 rows 221/222 (the scale column shows '100 %' against the CO2 row).