User's Manual

4.4 Communication between the WRAP and the Host Computer

4.4.1 Transaction Start

The user of the Hand Terminal sends data to the HOST. The user has

executed an action, e.g. pressed the OK-button or scanned a bar code.

The Hand Terminal user initiates sending by:

• Pressing the OK-button when the display shows the start frame

• Pressing a function key (F1-F10), which has been specified to

send a character string

• From input field which has been specified to send by pressing OK

or after reading with a laser scanner.

Sending sequence of the Hand Terminal consists of:

1. Counting and adding to the frame to be sent the CRC checksum

2. Generating a “processing data” text to the Hand Terminal’s

screen

3. Sending of the frame

4. Waiting for an answer from the HOST for a time defined by the

user as the limit for the timeout.

NOTE: It is not possible to execute any functions while waiting for the ack from

the Host system.

4.4.2 The WRAP receives a message from the Hand Terminal

Upon receiving a message from the Hand Terminal, the WRAP will:

•

Verify the integrity of the data frame using the CRC method.

If the frame is flawless, it will be forwarded to the RS232 serial interface and to

the network connection.

4.4.3 The HOST application receives the frame from the WRAP

The HOST application will receive the frame according to the RF650 HOST

protocol.

The HOST application has to execute the following checks before the frame

data can be given to business logic handling: