MODBUS_RTU_GET_SERIA(3)

💖 MODBUS_RTU_GET_SERIA(3) 💖

okay bestie, welcome to the libmodbus Manual — yes this is a real manual page and yes we're about to make it cute. sit down, hydrate, let's talk serial modes ✨

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🌸 NAME 🌸

modbus_rtu_get_serial_mode — bestie, it gets the current serial mode. that's the whole job. icon behaviour, honestly. 💅

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🦋 SYNOPSIS 🦋

int modbus_rtu_get_serial_mode(modbus_t *ctx);

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✨ DESCRIPTION ✨

so the way that modbus_rtu_get_serial_mode() works is it shall return the serial mode that your libmodbus context is currently vibing with. and there are exactly two (2) modes, no more, no less, and they are:

• MODBUS_RTU_RS232 — the serial line is set for RS232 communication. now, RS-232 (that's Recommended Standard 232, the full government name) is the traditional name for a series of standards for serial binary single-ended data and control signals, connecting between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment). it's commonly used in computer serial ports. the OG, the classic, the one that was there first. 🫶
• MODBUS_RTU_RS485 — the serial line is set for RS485 communication. EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems. this standard is widely used for communications in industrial automation because it can be used effectively over long distances and in electrically noisy environments. like, it ate and left no crumbs. long distance AND noisy?? main character energy fr fr 🔥

okay but the important caveat, no cap: this function is only available on Linux kernels 2.6.28 onwards, and it can only be used with a context using a RTU backend. if you're not on that kernel or not on RTU, this is not the function for you, sorry babe 😭

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🎀 RETURN VALUE 🎀

• if it's successful, the function shall return MODBUS_RTU_RS232 or MODBUS_RTU_RS485. slay.
• otherwise it shall return -1 and set errno to one of the values defined down below 👇

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💀 ERRORS 💀

• EINVAL — the current libmodbus backend is not RTU. that's it, that's the error. your backend is giving... not RTU. 🙈

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👑 AUTHORS 👑

the libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com>. thank you for your service, we are obsessed. 💜

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and that's the whole page bestie, you understood it, i'm so proud 🥹 this was libmodbus v3.1.6, dated 11/17/2025 — catch you on the next manpage, mwah 💋🌸✨