CHAPTER 13 RS-485 COMMUNICATIONS

13

(4) Definition of amplifier’s timings

Timings on the amplifier side are defined as follows:

FC

Information field

T1

Other

115200 bps：1.7 ms

than

-

38400 bps： 5 ms

10h

19200 bps： 10 ms

10h Other than below 9600 bps： 10 ms

Specify that n sets

of parameters or

Within (n+2)×10 ms

positioning data are

written in

T2

115200 bps：1.7 ms

38400 bps： 5 ms

19200 bps： 10 ms

9600 bps： 10 ms

Recommended

T3

timeout setting

Same

as T1

100 ms

250 ms

 Response time

It is able to specify a response time of the amplifier (T1) by PA2_94 (response time).

However, actual response time becomes {time for 3 characters + time for executing processing} (T0)

or longer.

* Although T0 varies depending on communications baud rate, FC, and so on, the shortest time is 2.5

ms for 38,400 bps.

If any time longer than T0 is specified, the amplifier responses after waiting for the specified time.

Master ：

Query

Amplifier：

T0

PA2-94 < T0

PA2-94 > T0

PA2-94

Response

PA2-94

Response

After the master has sent a query, if it takes a long time until the master switches into the receiving state,

set PA2_94 (response time) as needed because responses from the amplifiers might not be received

correctly.

3. Error processing

Errors are classified into the following:

(a) Physical/character-level errors

(b) Protocol level error (1)

(c) Protocol level error (2)

: Parity error, framing error, and so on

: CRC error

: Incorrect FC/address/data

13-34 Modbus RTU Communications