Owner's manual

Table Of Contents

Chapter 4 Multi-Drop Link Mode Control Procedure

Baud rate (for RS-485) Communication time (b)

Number of data Number of data Number of data

digits: 10 digits: 20 digits: 32

9600 bps 64 ms 74 ms 86 ms

38400 bps 28 ms 32 ms 37 ms

4.6 Communication Time Consideration

This section describes how to calculate the time required for data transmission and

for command transmission in multi-drop link mode.

■ How to calculate data transmission time

The following is the timing chart for multi-drop link mode communication .

Through the RS-485 communication between the N-400 and each BL series unit,

data transmission is constantly performed from the BL series to the N-400.

When the N-400 sends the polling command to a BL series with a specified ID

number, the data read by the BL series is sent to the host computer through the

RS-232C interface of the N-400.

* The above timing chart shows the case in which five BL series units are con-

nected.

Therefore, data transmission is delayed by a certain time duration until the polling

command is sent to the BL series after the BL series reads bar code data.

First, obtain the time duration required for the RS-485 data transmission.

In the RS-485 data transmission from the BL series to the N-400, the required time

varies depending on whether the BL series has stored bar code data (the BL series

has already read bar code data) or not.

In the above timing chart, “a” (the RS-485 data transmission time is short) shows

the case in which the BL series has stored no data, and “b” (the RS-485 data

transmission time is long) shows the case in which the BL series has stored some

data.

• a: RS-485 data transmission time required when the BL series has stored no

data

• b: RS-485 data transmission time required when the BL series has stored some

data

Baud rate (for RS-485) Communication time (a)

9600 bps 27.9 ms

38400 bps 12.8 ms

N400

(RS-485)

N400

(RS-232C)

Host

123 1234451123 23455

b a