-               status = ul_read(startconfigblock, ulev1_conf, sizeof(ulev1_conf));
-               if ( status == -1 ) {
-                       PrintAndLog("Error: tag didn't answer to READ EV1");
-                       ul_switch_off_field();
-                       return status;
-               } else if (status == 16) {
-                       // save AUTHENTICATION LIMITS for later:
-                       authlim = (ulev1_conf[4] & 0x07);
-                       ulev1_print_configuration(ulev1_conf);
-               } else {
-                       authlim=7;
+               if (startconfigblock){ // if we know where the config block is...
+                       status = ul_read(startconfigblock, ulev1_conf, sizeof(ulev1_conf));
+                       if ( status == -1 ) {
+                               PrintAndLog("Error: tag didn't answer to READ EV1");
+                               ul_switch_off_field();
+                               return status;
+                       } else if (status == 16) {
+                               // save AUTHENTICATION LIMITS for later:
+                               authlim = (ulev1_conf[4] & 0x07);
+                               ulev1_print_configuration(ulev1_conf);
+                       }