MODBUS_WRITE_BITS(3)

💖 MODBUS_WRITE_BITS 💖

okay bestie, so this one lives in the libmodbus Manual and it's literally the "set a whole bunch of coils at once" girlie. no cap. let's get into it 🫶

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✨ NAME ✨

modbus_write_bits — write many bits 🌈

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🎀 SYNOPSIS 🎀

int modbus_write_bits(modbus_t *ctx, int addr, int nb, const uint8_t *src);

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💅 DESCRIPTION 💅

so the modbus_write_bits() function shall write the status of the nb bits (coils) from src at the address addr of the remote device. that's the whole vibe, bestie — you're yeeting a whole pile of coil states at the remote device in one go instead of doing it one by one like a peasant. 👑

and listen, the src array must contain bytes set to TRUE or FALSE. that part is non-negotiable, it's giving "do not freestyle this". 💀

under the hood? the function uses the Modbus function code 0x0F (force multiple coils). iconic. main character energy fr fr. ✨

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⭐ RETURN VALUE ⭐

if everything slays, the function shall return the number of written bits. cute, we love a receipt. 💖

otherwise? it shall return -1 and set errno. 😭 that's your cue to do a vibe check on your inputs.

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🦋 ERRORS 🦋

• EMBMDATA — writing too many bits 🚨

bestie when this hits you were being way too ambitious with nb. the remote device said "no thank you ma'am." 🙈

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🌸 SEE ALSO 🌸

• modbus_read_bits(3)
• modbus_write_bit(3)

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👑 AUTHORS 👑

the libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com> 💜 shoutout to the legend, we stan.

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and that's the page, bestie!! this doc came to you courtesy of libmodbus v3.1.6, dated 11/17/2025 — periodt 💅✨