libmodbus/MIGRATION

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Migration notes from the 2.0 series (for 2.2)
=============================================

1 - modbus_init_rtu/tcp takes a new argument, the slave number of the device
    which established the connection.

2 - modbus_init_listen_tcp() has been renamed to modbus_slave_listen_tcp() and
    requires a new argument, the maximal number of connections:

int modbus_slave_init_tcp(modbus_param_t *mb_param, int nb_connection);


3 - New function modbus_slave_accept_tcp() to etablish a new connection
    (previously in modbus_init_listen_tcp()):

int modbus_slave_accept_tcp(modbus_param_t *mb_param, int *socket);


4 - modbus_listen() has been renamed to modbus_slave_receive() and requires a
    new argument, the socket file descriptor to listen on. If the sockfd is -1,
    the internal fd of modbus_param_t is used:

int modbus_slave_receive(modbus_param_t *mb_param, int sockfd,
                         uint8_t *query, int *query_length);


5 - If you use the HEADER_LENGTH_ defines, their values have been incremented by
    1 to reflect the PDU and ADU of the Modbus protocol and to reduce the CPU
    consumption:
     - HEADER_LENGTH_RTU           0 -> 1
     - HEADER_LENGTH_TCP           6 -> 7

6 - modbus_mapping_new returns 0 on success and -1 on failure.


=============================================
Migration notes from the 1.2 series (for 2.0)
=============================================

Init
====

modbus_init_tcp requires a third new argument, the port number.

modbus_init_tcp(modbus_param_t *mb_param, char *ip_address, int port)

Set the port to MODBUS_TCP_DEFAULT_PORT to use the default one
(502). It's convenient to use a port number greater than or equal to
1024 because it's not necessary to be root to use this port number.


Pointers of data
================

The coil and input status are now stored in an array of type uint8_t
(in 1.2.X series, array of type int was used).  So now, you need to
pass a pointer of type uint8_t to use read_coil_status(), for example.

The holding and input registers are now stored in an array of type
uint16_t.

These changes reduce the memory consumption.