'\" t
.\"     Title: modbus_reply_exception
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/15/2022
.\"    Manual: libmodbus Manual
.\"    Source: libmodbus v3.1.6
.\"  Language: English
.\"
.TH "MODBUS_REPLY_EXCEPTI" "3" "10/15/2022" "libmodbus v3\&.1\&.6" "libmodbus Manual"
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.nh
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.SH "NAME"
modbus_reply_exception \- send an exception response
.SH "SYNOPSIS"
.sp
*int modbus_reply_exception(modbus_t *\fIctx\fR, const uint8_t *\fIreq\fR, unsigned int \fIexception_code\fR);
.SH "DESCRIPTION"
.sp
The \fBmodbus_reply_exception()\fR function shall send an exception response based on the \fIexception_code\fR in argument\&.
.sp
The libmodbus provides the following exception codes:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_ILLEGAL_FUNCTION (1)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_ILLEGAL_DATA_ADDRESS (2)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_ILLEGAL_DATA_VALUE (3)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_SLAVE_OR_SERVER_FAILURE (4)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_ACKNOWLEDGE (5)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_SLAVE_OR_SERVER_BUSY (6)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_NEGATIVE_ACKNOWLEDGE (7)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_MEMORY_PARITY (8)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_NOT_DEFINED (9)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_GATEWAY_PATH (10)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
MODBUS_EXCEPTION_GATEWAY_TARGET (11)
.RE
.sp
The initial request \fIreq\fR is required to build a valid response\&.
.SH "RETURN VALUE"
.sp
The function shall return the length of the response sent if successful\&. Otherwise it shall return \-1 and set errno\&.
.SH "ERRORS"
.PP
\fBEINVAL\fR
.RS 4
The exception code is invalid
.RE
.SH "SEE ALSO"
.sp
\fBmodbus_reply\fR(3) \fBlibmodbus\fR(7)
.SH "AUTHORS"
.sp
The libmodbus documentation was written by Stéphane Raimbault <stephane\&.raimbault@gmail\&.com>