Echelon Neuron C - Manual (Page 174)

154 Functions
}
update_nv( ) Function
The update_nv( ) function copies from the structure referenced by the nv-entry
pointer parameter to the network variable configuration table entry as specified
by the index parameter.
Important: This function has a mechanism that ensures that a reset or power
cycle during an EEPROM modification does not cause the device to go
unconfigured. This mechanism uses the error log to serve as a semaphore. Thus,
the error log is written to on every call to this function, even if the net effect of
the function is to not modify or write to the configuration data at all (because the
new contents match the old). Applications must minimize calls to this function to
ensure that the maximum number of supported writes for EEPROM is not
exceeded over the lifetime of the application.
See the ISO/IEC 14908 (ANSI/EIA/CEA-709.1) Control Network Specification for
a description of the data structure.
Syntax
#include <access.h>
void update_nv (const nv_struct *
nv-entry , int index );
Example
#include <access.h>
nv_struct nv_copy;
network output SNVT_switch nvoSwitch;
void f(void)
{
nv_copy = *access_nv(nv_table_index(nvoSwitch));
// Modify the nv_copy here as necessary
...
update_nv(&nv_copy,nv_table_index(nvoSwitch));
}
update_program_id( ) Function
The update_program_id( ) function copies the 8-byte array referenced by the
pid_p pointer parameter to the program ID stored in the device’s EEPROM.
Important: This function has a mechanism that ensures that a reset or power
cycle during an EEPROM modification does not cause the device to go
unconfigured. This mechanism uses the error log to serve as a semaphore. Thus,
the error log is written to on every call to this function, even if the net effect of
the function is to not modify or write to the configuration data at all (because the
new contents match the old). Applications must minimize calls to this function to
ensure that the maximum number of supported writes for EEPROM is not
exceeded over the lifetime of the application.