找了几天，终于发现论坛里3年前就有人问过了，但是没有结果，并且由于帖子太老无法直接回复，特发此帖
我也遇到了相同的情况，设551＝3，USB连接变频器后，用英文版SW3（含SW1的那个版本）读会报错，记录文件如下：
--------------------------------------------------------------------------------
St. No. 0
Model: FR-A740-7.5K-CHT
Capacity: 7.5
Option 1: -------
Option 2: -------
Option 3: -------
Comment:

--------------------------------------------------------------------------------
Reading Error
+-----+--------------------------------------------------+----------+----------+
|NO.  |Name                                              |Initial   |Error No. |
+-----+--------------------------------------------------+----------+----------+
| 260 |PWM frequency automatic switchover                |       1  | 80010016 |
| 414 |PLC function operation selection                  |       0  | 80010016 |
| 415 |Inverter operation lock mode setting              |       0  | 80010016 |
| 416 |Pre-scale function selection                      |       0  | 80010016 |
| 417 |Pre-scale setting value                           |       1  | 80010016 |
| 498 |PLC function flash memory clear                   |       0  | 80010016 |
| 506 |Parameter 1 for user                              |       0  | 80010016 |
| 507 |Parameter 2 for user                              |       0  | 80010016 |
| 508 |Parameter 3 for user                              |       0  | 80010016 |
| 509 |Parameter 4 for user                              |       0  | 80010016 |
| 510 |Parameter 5 for user                              |       0  | 80010016 |
| 511 |Parameter 6 for user                              |       0  | 80010016 |
| 512 |Parameter 7 for user                              |       0  | 80010016 |
| 513 |Parameter 8 for user                              |       0  | 80010016 |
| 514 |Parameter 9 for user                              |       0  | 80010016 |
| 515 |Parameter 10 for user                             |       0  | 80010016 |
+-----+--------------------------------------------------+----------+----------+
Total = 16

--------------------------------------------------------------------------------
FR Configurator SW3 Ver. 3.00
Date:06-09-2015 13:58:37
Communication:USB/1/19200/8/2/EVEN/CR/NONE
OS:Windows XP Professional Service Pack 3
CPU:Intel(R) Pentium(R) Dual  CPU  T2390  @ 1.86GHz
Clock:1.86GHz
--------------------------------------------------------------------------------

請使用V5版的軟體試試