'\" t
.\"     Title: modbus_mask_write_register
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 02/28/2020
.\"    Manual: libmodbus Manual
.\"    Source: libmodbus v3.1.6
.\"  Language: English
.\"
.TH "MODBUS_MASK_WRITE_RE" "3" "02/28/2020" "libmodbus v3\&.1\&.6" "libmodbus Manual"
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.SH "NAME"
modbus_mask_write_register \- mask a single register
.SH "SYNOPSIS"
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\fBint modbus_mask_write_register(modbus_t *\fR\fB\fIctx\fR\fR\fB, int \fR\fB\fIaddr\fR\fR\fB, uint16_t \fR\fB\fIand\fR\fR\fB, uint16_t \fR\fB\fIor\fR\fR\fB);\fR
.SH "DESCRIPTION"
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The \fBmodbus_mask_write_register()\fR function shall modify the value of the holding register at the address \fIaddr\fR of the remote device using the algorithm:
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.if n \{\
.RS 4
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new value = (current value AND \*(Aqand\*(Aq) OR (\*(Aqor\*(Aq AND (NOT \*(Aqand\*(Aq))
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.if n \{\
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The function uses the Modbus function code 0x16 (mask single register)\&.
.SH "RETURN VALUE"
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The function shall return 1 if successful\&. Otherwise it shall return \-1 and set errno\&.
.SH "SEE ALSO"
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\fBmodbus_read_registers\fR(3) \fBmodbus_write_registers\fR(3)
.SH "AUTHORS"
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Martijn de Gouw <martijn\&.de\&.gouw@prodrive\&.nl> The libmodbus documentation was written by Stéphane Raimbault <stephane\&.raimbault@gmail\&.com>