VT634_reply_080930

Replies to Mｒ. WangXun’s questions inqured on an email dated on 23rd September through Mr. John Q Zhang are as follows.

1) 2mS sampling time of sensor feedback

According to MDS recommendation, TR can use 2 pulse sensor. If TR motor is 6000cpm, there is 200 pulse per second, equal to 1 pulse every 5mS. In this case, VT634 can not receive a pulse in 2mS, how can controller calculate every 2mS ?

(Ans.)

VT634 monitors a pulse every 2ms, and speed calculation is implemented when a pulse is detected. Interval of the calculation cycle gets longer when a number of pulses are small, but TR speed change in 2ms is not so large, so that it dose not affect so much on TR control.

2ms 2ms 2ms

Speed is calculated from the time

when the latest pulse came.

When pulse does not come, the latest speed is hold.

* Reasons that Meiden recommends 2 pulse ABA

A

B

Using 2 pulse, distinction of the same edge is easy as shown on an upper-left picture. Absolute position error will not depend on gear’s accuracy error.

2) Pls refer to attached modbus manual, Wang San has some questions:

2.1) Page 11, Command example: register number is 000A, it is 16x10=160bit, but

response is 96+48=144bit, command and response bit are not same, why ?

(Ans.)

Instruction manual provided in a meeting this September in Beijing 2008 was wrong. ”96+” is correct. Please see appendix 1.

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2.2) Page 13&14, Command example: start address is 03E9 and 03EB to A021, Does

VT634 use same start address (03E9 and 03EB) to other parameters ?

(Ans.)

As shown on table 6-1 on ST-3461, please use the same address for start address regardless any parameter number. Ex.

Multiplexed data write (10h) : 03EB （03EC-1）

Multiplexed data read (03h) : 03E9 （03EA-1）

2.3) VT634 has many parameters, what is their data type, such as 8bit or 16bit or

32bit? sign or not?

(Ans.)

Monitor data read (03h) and Command data write (03h) is 16bit（WORD） data type as shown on table1 and table2 on page 4 of reference “VT634_Modbus追加機能.pdf “, which is the one provided in the meeting. Regarding “sign”, please refer to Chapter 4 “Control function and parameter settings” on instruction manual ST-3459.

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Revision History

6-3-3. Function code: 03h (fault buffer read)

The fault information designated with the start address is read.

The start address and fault information correspond as shown below. The fault information is stored in #1 to #8 in order from new to old.

Start address

00h 006Eh 0078h 0082h

Response data Fault information #1 Fault information #2 Fault information #3 Fault information #4

Start address

008Ch 0096h 00A0h 00AAh

Response data Fault information #5 Fault information #6 Fault information #7 Fault information #8

1) Command

Example)

Example)

(*1)

0 3 0 0 6 3 0 0 0 A

Function(8bit)

Start address No. of registers

(16bit) (16bit)

(*2)

2) Normal response

0 3 1 4 0 0 0 4 0 • • • 0 0 3 E 8 0 0 0 • • • 0 0 0 Function

(8bit)

No. of bytes (8bit)

Fault information

(96bit)

⇓Spare data (48bit) bit

0 0 0 4 0 0 0 5 0 0 0 0 2 7 1 0 0 0 0 0 0 3 E 8 Fault code (1st) Fault code (2nd) Output frequency at fault(16bit) (16bit) (32bit)

Primary current at fault (32bit)

Two fault causes, and the output frequency and output current at fault occurrence are recorded as the fault information.

The low-order digit is 0.01Hz for the output frequency, and 0.1A for the output current.

Refer to \"VT634 Instruction Manual (Document No.: ST-3459)\" for details on the error codes.

3) Error response

Example)

8 3 0 2

FunctionExceptional code (8bit) (8bit)

*1 : In the examples, a space is inserted to delimit each function. Do not insert the spaces when actually

inputting the command. The spaces are also not displayed in the response. *2 : Designate the \"actual start address-1\" value.

This is (00h-1) for fault information #1.