MODBUS_READ_INPUT_BI(3)

💖 MODBUS_READ_INPUT_BI 💖

okay bestie, so this is a page from the libmodbus manual, and today we're learning about modbus_read_input_bits 🦋 like literally the moment has arrived and I'm obsessed.

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✨ NAME ✨

modbus_read_input_bits — read many input bits 🎀

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🌸 SYNOPSIS 🌸

int modbus_read_input_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest);

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💅 DESCRIPTION 💅

okay so the modbus_read_input_bits() function shall read the content of the nb input bits to the address addr of the remote device 🫶 no cap, that's the whole job. The result of reading is stored in the dest array as unsigned bytes (8 bits) set to TRUE or FALSE. iconic behaviour honestly ✨

⚠️ bestie listen to me, this part is important: you must take care to allocate enough memory to store the results in dest — at least nb * sizeof(uint8_t). not enough memory = not the vibe. do not skip this, fr fr 😭

the function uses the Modbus function code 0x02 (read input status) 💜

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🔥 RETURN VALUE 🔥

if it works, the function shall return the number of read input status 🌈 slay. otherwise it shall return -1 and set errno. it's giving "we tried" 💀

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🎀 ERRORS 🎀

• EMBMDATA — Too many discrete inputs requested. bestie you asked for so many bits. the limit said no 🙈

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👑 SEE ALSO 👑

• modbus_read_input_registers(3)

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🌟 AUTHORS 🌟

the libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com> — actual legend, we thank you for your service 🫶💖

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aaaand that's the whole page bestie, you ate that 🧚✨ this has been libmodbus v3.1.6, dated 11/17/2025, and honestly? iconic. periodt 💅🌸