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=============================================
Migration notes from the 2.0 series (for 3.0)
=============================================
The 3.0 release use a brand new API and this document covers only the general
changes:
- the structure modbus_param_t is gone and is replaced by a new opaque and
dynamically allocated structure modbus_t.
- the slave argument is no more an argument of the Modbus functions, you need to
call modbus_set_slave first.
- the public header file is smaller so some internal defines aren't accessible
anymore.
- all function and constants are respectively prefixed by modbus_ or MODBUS_.
- the POSIX error conventions are used (if an error occured, -1 or NULL is
returned and errno is set accordingly).
- coil status and discretes inputs are just bits and force/preset actions have
been renamed to write actions.
We hope you'll enjoy the new API to accept the migration burden!
=============================================
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.
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