Citizen Systems CLP-8301 User Manual

Page 68

Chapter 8 Maintenance

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DTR protocol

DTR signal “Ready (High)” level requirements:

The following must be satisfied:

· Printer is on line.
· Receive buffer has more than 128 bytes available.

Note: When receive buffer has less than 128 bytes available, DTR signal becomes “Busy

(Low)” level and this “Busy (Low) level is kept until receive buffer has at least 1K bytes

available.

DTR signal “Busy (Low)” level requirements:

The following must be satisfied:

· Printer is in error.
· Printer is in paused state.
· Receive buffer has less than 128 bytes available.

Pin assignment

Pin No.

Signal

Input/Output

Description

1 FG

Output

Frame

ground

7 SGND

Output

Signal

ground

TXD

Output

Signal to transmit data

RXD

Input

Signal to receive data

4 RTS

Output

Transmission request signal. Pull up to +12V with
3.3Kohm

6 DSR

Input

Signal active when host computer ready to interface with
printer

20 DTR

Output

Signal active when printer ready to interface with host
computer

25 VCC

Output

(Factory

use)