Experimental Physics and
Industrial Control System

Hi:

Klemen found that the EGU field for ai is STRING[16] and he can set an EGU field accordingly:
$ caput BL11A:Det:crocD2:Y1:RateTrigger.EGU "abcdefghijklmnop"
Old : BL11A:Det:crocD2:Y1:RateTrigger.EGU 123456789012345
New : BL11A:Det:crocD2:Y1:RateTrigger.EGU abcdefghijklmno

The channel access protocol, however, only gives us a MAX_UNITS_SIZE of 8 in db_access.h:

 #define MAX_UNITS_SIZE          8

 /* structure for a control double field */
struct dbr_ctrl_double{
        dbr_short_t     status;                 /* status of value */
        dbr_short_t     severity;               /* severity of alarm */
        dbr_short_t     precision;              /* number of decimal places */
        dbr_short_t     RISC_pad0;              /* RISC alignment */
        char            units[MAX_UNITS_SIZE];  /* units of value */
        dbr_double_t    upper_disp_limit;       /* upper limit of graph */
        dbr_double_t    lower_disp_limit;       /* lower limit of graph */
        dbr_double_t    upper_alarm_limit;
        dbr_double_t    upper_warning_limit;
        dbr_double_t    lower_warning_limit;
        dbr_double_t    lower_alarm_limit;
        dbr_double_t    upper_ctrl_limit;       /* upper control limit */
        dbr_double_t    lower_ctrl_limit;       /* lower control limit */
        dbr_double_t    value;                  /* current value */
};


Does anybody remember the reasoning for this?
Would it make sense to shorten the EGU field length in records?
Or lengthen MAX_UNITS_SIZE?
Or was this done in anticipation of 2-byte characters for units ;-) ?

-Kay