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modbus_receive_confirmation(3)
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NAME
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modbus_receive_confirmation - receive a confirmation request
SYNOPSIS
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*int modbus_receive_confirmation(modbus_t *'ctx', uint8_t *'rsp');*
DESCRIPTION
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The *modbus_receive_confirmation()* function shall receive a request via the
socket of the context _ctx_. This function must be used for debugging purposes
because the received response isn't checked against the initial request. This
function can be used to receive request not handled by the library.
The maximum size of the response depends on the used backend, in RTU the _rsp_
array must be _MODBUS_RTU_MAX_ADU_LENGTH_ bytes and in TCP it must be
_MODBUS_TCP_MAX_ADU_LENGTH_ bytes. If you want to write code compatible with
both, you can use the constant _MODBUS_MAX_ADU_LENGTH_ (maximum value of all
libmodbus backends). Take care to allocate enough memory to store responses to
avoid crashes of your server.
RETURN VALUE
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The function shall store the confirmation request in _rsp_ and return the
response length if sucessful. The returned request length can be zero if the
indication request is ignored (eg. a query for another slave in RTU
mode). Otherwise it shall return -1 and set errno.
EXAMPLE
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[source,c]
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uint8_t rsp[MODBUS_MAX_ADU_LENGTH];
rc = modbus_receive_confirmation(ctx, rsp);
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SEE ALSO
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linkmb:modbus_send_raw_request[3]
AUTHORS
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The libmodbus documentation was written by Stéphane Raimbault
<stephane.raimbault@gmail.com>