plc_done() is used to shut down the library and private memory map for the module. This should be done if the module exits for any reason.

Limitation: The plc_done() function is not particularly complete - it should shut down the module completely, deallocate everything and generally clean the slate enough so that plc_init() could be called again. This is not currently done, mostly through carelessness and because most of the examples are infinite loops, and the rest exit immediately after calling plc_done(). Please file a bug report or ask on the list if you need this fixed.

Return values: plc_init() and plc_done() return returns 0 on success, -1 on failure.

plc_init(module_name, argc, argv);

plc_done();

Normal usage of these functions is described in the basic custom module chapter. In general terms, plc_scan_beg() should be the first thing in a scan, and plc_scan_end() the last.

Scans should not in general be nested; that is, make sure that these functions are called in alternation. For instance, if you have a long-running loop within your program, you might do the following in the middle:

  plc_update() /* update outputs (may be omitted if nothing was plc_set()) */
  plc_scan_end() /* end scan */
  plc_scan_beg() /* begin new scan */
  plc_update() /* update inputs */

If a module does not have discernible scans, these two functions can be omitted altogether. However, synch, scan_period and similar functionality will not be available for modules that don't call these functions.

Return values: FIXME

int plc_scan_beg(void);
int plc_scan_end(void);

const char *plc_module_name(void);

Note: this is only applicable if you pass the real argc and argv to plc_init(). If you don't pass argv in, it can't do much about it...

Return values: FIXME

int plc_print_usage(FILE *output);

int plc_init_try(char const *module_name, int argc, char **argv);

#define CLO_LEADER "--PLC"

#define CLO_plc_id             CLO_LEADER "plc_id="
#define CLO_loc_local          CLO_LEADER "local"
#define CLO_loc_isolate        CLO_LEADER "isolate"
#define CLO_loc_shared         CLO_LEADER "shared"
#define CLO_privmap_key        CLO_LEADER "local_map_key="
#define CLO_log_level          CLO_LEADER "debug="
#define CLO_log_file           CLO_LEADER "logfile="
#define CLO_config_file        CLO_LEADER "conf="
#define CLO_module_name        CLO_LEADER "module="
#define CLO_force_init         CLO_LEADER "force-init"