diff -r 542bdc7f6522 -r 16079aef4c4c bmsd/mysql.c
--- a/bmsd/mysql.c	Wed Aug 23 10:30:09 2023 +0200
+++ b/bmsd/mysql.c	Thu Oct 12 14:19:46 2023 +0200
@@ -308,6 +308,8 @@
 		ispindel->og_gravity	      = atof(row[15]);
 		ispindel->yeast_lo	      = atof(row[16]);
 		ispindel->yeast_hi	      = atof(row[17]);
+		ispindel->calibrate           = xstrcpy(row[18]);
+		ispindel->lastseen            = datetime_to_time_t(row[19]);
 
                 if (ispindels == NULL) {
                     ispindels = ispindel;
@@ -360,6 +362,8 @@
             free(tmpi->beeruuid);
 	if (tmpi->mode)
 	    free(tmpi->mode);
+	if (tmpi->calibrate)
+	    free(tmpi->calibrate);
         free(tmpi);
     }
 
@@ -710,17 +714,63 @@
 
 
 
+/*
+ * Update the gravity calculated from the calibrate data.
+ */
+double ispindel_mysql_plato(char *uuid, double angle)
+{
+    char		*query = malloc(1024), *cal;
+    struct json_object	*jobj, *metric, *val;
+    double		poly[4], plato = 0;
+
+    snprintf(query, 1023, "SELECT uuid,calibrate FROM mon_ispindels WHERE uuid='%s'", uuid);
+    if (mysql_query(con, query)) {
+	syslog(LOG_NOTICE, "MySQL: %s error %u (%s))", query, mysql_errno(con), mysql_error(con));
+	free(query);
+	return 0.0;
+    }
+
+    res_set = mysql_store_result(con);
+    if (res_set == NULL) {
+	syslog(LOG_NOTICE, "MySQL: mysq_store_result error %u (%s))", mysql_errno(con), mysql_error(con));
+	free(query);
+	return 0.0;
+    }
+    free(query);
+
+    if ((row = mysql_fetch_row(res_set)) != NULL) {
+    	cal = xstrcpy(row[1]);
+	jobj = json_tokener_parse(cal);
+	if (json_object_object_get_ex(jobj, "polyData", &metric)) {
+	    int arraylen = json_object_array_length(metric);
+	    for (int i = 0; i < arraylen; i++) {
+		val = json_object_array_get_idx(metric, i);
+		poly[i] = json_object_get_double(val);
+	    }
+	    plato = (poly[0] * pow(angle, 3)) + (poly[1] * pow(angle, 2)) + (poly[2] * angle) + poly[3];
+	}
+	free(cal);
+    }
+    return plato;
+}
+
+
 void ispindel_mysql_insert(sys_ispindel_list *ispindel)
 {
-    char        *query = malloc(2560);
+    char        *query = malloc(2560), last[73];
+    struct tm   *mytime;
+
+    mytime = localtime(&ispindel->lastseen);
+    snprintf(last, 64, "%04d-%02d-%02d %02d:%02d:%02d",
+        mytime->tm_year + 1900, mytime->tm_mon + 1, mytime->tm_mday, mytime->tm_hour, mytime->tm_min, mytime->tm_sec);
 
     snprintf(query, 2559,
         "INSERT INTO mon_ispindels SET uuid='%s', alias='%s', node='%s', online='%d', mode='%s', alarm='%d', " \
         "angle='%.6f', temperature='%.4f', battery='%.6f', gravity='%.6f', up_interval='%d', og_gravity='0.0', " \
-	"yeast_lo='%.1f', yeast_hi='%.1f'",
+	"yeast_lo='%.1f', yeast_hi='%.1f', lastseen='%s'",
         ispindel->uuid, ispindel->alias, ispindel->node, ispindel->online ? 1:0, ispindel->mode, ispindel->alarm,
         ispindel->angle, ispindel->temperature, ispindel->battery, ispindel->gravity, ispindel->interval,
-	ispindel->yeast_lo, ispindel->yeast_hi);
+	ispindel->yeast_lo, ispindel->yeast_hi, last);
 
     if (bms_mysql_query(query) == 0) {
         syslog(LOG_NOTICE,  "MySQL: insert new ispindel %s", ispindel->node);
@@ -732,15 +782,23 @@
 
 void ispindel_mysql_update(sys_ispindel_list *ispindel)
 {
-    char        *query = malloc(2560);
+    char        *query = malloc(2560), last[73];
+    struct tm   *mytime;
 
+    mytime = localtime(&ispindel->lastseen);
+    snprintf(last, 64, "%04d-%02d-%02d %02d:%02d:%02d",
+        mytime->tm_year + 1900, mytime->tm_mon + 1, mytime->tm_mday, mytime->tm_hour, mytime->tm_min, mytime->tm_sec);
+
+    /*
+     * Do not update the calibrate field with regular updates.
+     */
     snprintf(query, 2559,
         "UPDATE mon_ispindels SET online='%d', mode='%s', alias='%s', alarm='%d', " \
 	"angle='%.6f', temperature='%.4f', battery='%.6f', gravity='%.6f', up_interval='%d', og_gravity=GREATEST(og_gravity, '%.6f'), " \
-        "yeast_lo='%.1f', yeast_hi='%.1f' WHERE uuid='%s'",
+        "yeast_lo='%.1f', yeast_hi='%.1f', lastseen='%s' WHERE uuid='%s'",
         ispindel->online ? 1:0, ispindel->mode, ispindel->alias, ispindel->alarm,
 	ispindel->angle, ispindel->temperature, ispindel->battery, ispindel->gravity, ispindel->interval, ispindel->gravity,
-	ispindel->yeast_lo, ispindel->yeast_hi, ispindel->uuid);
+	ispindel->yeast_lo, ispindel->yeast_hi, last, ispindel->uuid);
     bms_mysql_query(query);
     free(query);
 }