modbus_set_slave(3) [debian man page]

MODBUS_SET_SLAVE(3)						 Libmodbus Manual					       MODBUS_SET_SLAVE(3)

NAME

       modbus_set_slave - set slave number in the context

SYNOPSIS

       int modbus_set_slave(modbus_t *ctx, int slave);

DESCRIPTION

       The modbus_set_slave() function shall set the slave number in the libmodbus context.

       The behavior depends of network and the role of the device:

       RTU
	   Define the slave ID of the remote device to talk in master mode or set the internal slave ID in slave mode. According to the protocol,
	   a Modbus device must only accept message holing its slave number or the special broadcast number.

       TCP
	   The slave number is only required in TCP if the message must reach a device on a serial network. The special value MODBUS_TCP_SLAVE
	   (0xFF) can be used in TCP mode to restore the default value.

       The broadcast address is MODBUS_BROADCAST_ADDRESS. This special value must be use when you want all Modbus devices of the network receive
       the request.

RETURN VALUE

       The modbus_set_slave() function shall return 0 if successful. Otherwise it shall return -1 and set errno to one of the values defined
       below.

ERRORS

       EINVAL
	   The slave number is invalid.

AUTHORS

       The libmodbus documentation was written by Stephane Raimbault <stephane.raimbault@gmail.com[1]>

NOTES

	1. stephane.raimbault@gmail.com
	   mailto:stephane.raimbault@gmail.com

libmodbus 3.0.3 						    05/26/2012						       MODBUS_SET_SLAVE(3)

MODBUS_NEW_TCP_PI(3)						 Libmodbus Manual					      MODBUS_NEW_TCP_PI(3)

NAME

       modbus_new_tcp_pi - create a libmodbus context for TCP Protocol Independent

SYNOPSIS

       modbus_t *modbus_new_tcp_pi(const char *node, const char *service);

DESCRIPTION

       The modbus_new_tcp_pi() function shall allocate and initialize a modbus_t structure to communicate with a Modbus TCP IPv4 or Ipv6 server.

       The node argument specifies the host name or IP address of the host to connect to, eg. 192.168.0.5 , ::1 or server.com.

       The service argument is the service name/port number to connect to. To use the default Modbus port use the string "502". On many Unix
       systems, it's convenient to use a port number greater than or equal to 1024 because it's not necessary to have administrator privileges.

RETURN VALUE

       The modbus_new_tcp_pi() function shall return a pointer to a modbus_t structure if successful. Otherwise it shall return NULL and set errno
       to one of the values defined below.

ERRORS

       EINVAL
	   The node string is empty or has been truncated. The service string is empty or has been truncated.

EXAMPLE

	   modbus_t *ctx;

	   ctx = modbus_new_tcp_pi("::1", "1502");
	   if (ctx == NULL) {
	       fprintf(stderr, "Unable to allocate libmodbus context
");
	       return -1;
	   }

	   if (modbus_connect(ctx) == -1) {
	       fprintf(stderr, "Connection failed: %s
", modbus_strerror(errno));
	       modbus_free(ctx);
	       return -1;
	   }

SEE ALSO

       modbus_new_tcp(3) modbus_new_rtu(3) modbus_free(3)

AUTHORS

       The libmodbus documentation was written by Stephane Raimbault <stephane.raimbault@gmail.com[1]>

NOTES

	1. stephane.raimbault@gmail.com
	   mailto:stephane.raimbault@gmail.com

libmodbus 3.0.3 						    05/26/2012						      MODBUS_NEW_TCP_PI(3)