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# modbus_read_bits
## Name
modbus_read_bits - read many bits
## Synopsis
```c
int modbus_read_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest);
```
## Description
The *modbus_read_bits()* function shall read the status of the `nb` bits (coils)
to the address `addr` of the remote device. The result of reading is stored in
`dest` array as unsigned bytes (8 bits) set to `TRUE` or `FALSE`.
You must take care to allocate enough memory to store the results in `dest`
(at least `nb * sizeof(uint8_t)`).
The function uses the Modbus function code 0x01 (read coil status).
## Return value
The function shall return the number of read bits if successful. Otherwise it
shall return -1 and set errno.
## Errors
- *EMBMDATA*, too many bits requested
## See also
- [modbus_write_bit](modbus_write_bit.md)
- [modbus_write_bits](modbus_write_bits.md)
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