v3.2.0

libmodbus 3.2.0 (2026-07-02)

• Add modbus_proxy() to bridge two Modbus backends (closes #70).
• Add termios2 support to allow custom baud rates (RTU).
• Return an exception response for READ EXCEPTION STATUS (0x07).
• Use EMBXILVAL instead of EMBMDATA for illegal data value errors.
• modbus_reply: reject NULL req and mb_mapping arguments.
• modbus_reply: validate request length before reading per-function fields.
• Fix signed integer overflow in modbus_get_float_*() (reported by Dominik
  Blain and Henrik Brodin).
• Fix signed integer overflow in the MODBUS_GET_INT*_FROM_INT* macros;
  MODBUS_GET_INT16_FROM_INT8() now returns a signed int16_t in every context
  (reported by Henrik Brodin - Trail of Bits).
• Fix strict aliasing violation in modbus_set_float_*() by using memcpy
  (reported by Henrik Brodin).
• Remove dead code (Coverity CID 561619).
• modbus-rtu: don't use O_EXCL when opening the device (#760).
• WIN32 compatibility for setsockopt() in modbus-tcp.c (#800).
• Check if ai_list is null before freeing it (#831).
• Respect user-provided CFLAGS (closes #836).
• Fix test to use ctx instead of invalid_ctx (closes #791, #792).
• Update documentation of float functions (closes #838).
• Fix documentation examples of modbus_get_float_* functions.
• modbus_reply_exception: reject a NULL request pointer.
• modbus_mask_write_register: validate that ctx is not NULL.
• modbus_write_and_read_registers: validate src/dest pointers and counts.
• modbus_report_slave_id: reject a NULL dest buffer.
• modbus_get_*_timeout: validate that the output pointers are not NULL.
• modbus_mapping_new_start_address: cap table dimensions.
• modbus_mapping_new: reject negative counts.
• modbus_rtu_set_custom_rts: reject a NULL callback.
• modbus-rtu: avoid integer overflow in the RTS post-send delay.
• modbus-rtu: check the return values of the RTS ioctl calls.
• modbus-rtu: check the return value when saving termios settings on connect.
• modbus-rtu: report a failure to restore termios settings on close.
• modbus_new_rtu: reject negative baud rates.
• modbus-tcp: guard freeaddrinfo() against NULL on resolver failure.
• modbus_new_tcp: NUL-terminate the IP string when ip is NULL.
• modbus_reply: validate FC22 request length before writing the register.
• modbus-tcp: keep ctx->s consistent across failed or repeated connects (no
  false success on a stale descriptor, no socket leak on reconnect).
• modbus-tcp: don't override the user error recovery mode in the flush overflow
  path.
• modbus-tcp: fully initialize the sigaction struct for the SIGPIPE handler on
  BSD.
• modbus-rtu: fix the Windows serial handle lifecycle (initialize the handle,
  guard close against a never-opened handle and reset it after close).
• modbus-rtu: sleep the RTS turnaround delay in chunks to stay portable with
  usleep().
• modbus_new_rtu: validate data_bit and stop_bit arguments.
• modbus_send_raw_request_tid: reject NULL raw_req with EINVAL.
• modbus_get_byte_from_bits: remove an always-false assert and clamp nb_bits
  consistently in debug and release builds.
• Preserve errno across the Windows error-recovery paths.
• tests: don't kill the unit test server on RTU bad-CRC frames.
• tests: fix integer overflow in the bandwidth-client rate computation.

New Contributors

• @micrictor made their first contribution in #831
• @desteemy made their first contribution in #800

Full Changelog: v3.1.12...v3.2.0