MODBUS_STRERROR(3)

💖 MODBUS_STRERROR(3) — bestie's guide to error messages 💖

okay so this is a page from the libmodbus Manual, and it's about one little function that is genuinely SO underrated. like everyone's out here calling strerror() and being confused, and meanwhile modbus_strerror is right there being an icon. 💅

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✨ NAME ✨

modbus_strerror — return the error message 🫶

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✨ SYNOPSIS ✨

const char *modbus_strerror(int errnum);

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✨ DESCRIPTION ✨

so the modbus_strerror() function shall return a pointer to an error message string corresponding to the error number that you hand it in the errnum argument. simple as that, no notes. 🌸

here's the tea tho 🍓: libmodbus defines additional error numbers over and above the ones your operating system already defines. which means applications should use modbus_strerror() in preference to the standard strerror() function. like, if you call plain old strerror() you're literally leaving messages on the table. bestie. use the modbus one. iykyk. 👑

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✨ RETURN VALUE ✨

the modbus_strerror() function shall return a pointer to an error message string. that's it, that's the whole vibe. ✨

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✨ ERRORS ✨

no errors are defined. none. zero. the vibe check is immaculate. 💀✨

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✨ EXAMPLE ✨

okay so picture this: you wanna display an error message when a Modbus connection cannot be established. here's how you do it 👇

if (modbus_connect(ctx) == -1) {
    fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
    abort();
}

see how it's passing errno in there? yeah. chef's kiss. ate. 🔥

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✨ SEE ALSO ✨

linkmb:libmodbus — go read the rest, fr fr 💜

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✨ AUTHORS ✨

the libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com>. we love an author who documents things properly. 👑🫶

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libmodbus v3.1.6 · 11/17/2025 — that's the version and date bestie, mwah, go forth and print good error messages 🎀🦋💖