modbus_write_and_read_registers(3)

1MODBUS_WRITE_AND_REA(3)        Libmodbus Manual        MODBUS_WRITE_AND_REA(3)
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NAME

6       modbus_write_and_read_registers - write and read many registers in a
7       single transaction
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SYNOPSIS

10       int modbus_write_and_read_registers(modbus_t *ctx, int write_addr, int
11       write_nb, const uint16_t *src, int read_addr, int read_nb, const
12       uint16_t *dest);
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DESCRIPTION

15       The modbus_write_and_read_registers() function shall write the content
16       of the write_nb holding registers from the array src to the address
17       write_addr of the remote device then shall read the content of the
18       read_nb holding registers to the address read_addr of the remote
19       device. The result of reading is stored in dest array as word values
20       (16 bits).
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22       You must take care to allocate enough memory to store the results in
23       dest (at least nb * sizeof(uint16_t)).
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25       The function uses the Modbus function code 0x17 (write/read registers).
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RETURN VALUE

28       The modbus_write_and_read_registers() function shall return the number
29       of read registers if successful. Otherwise it shall return -1 and set
30       errno.
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ERRORS

33       EMBMDATA
34           Too many registers requested, Too many registers to write
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AUTHORS

41       The libmodbus documentation was written by Stéphane Raimbault
42       <stephane.raimbault@gmail.com[1]>
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NOTES

45        1. stephane.raimbault@gmail.com
46           mailto:stephane.raimbault@gmail.com
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50libmodbus 3.0.8                   07/31/2019           MODBUS_WRITE_AND_REA(3)