Intermec ED40, Integration Manual, Page: 71 / 155

Chapter 5 — Firmware Download
ED40 Decode Board Integration Guide 59
Example
RTS/CTS Transmission Example
Transmission from the host to the imager
• A: The host transmits a byte to the imager without using the hardware
protocol.
Transmission from the imager to the host
• B-1: The imager requests permission to transmit a byte.
• B-2: The host grants permission to the imager.
• B-3: The imager transmits the byte.
• B-4: The imager removes the request.
• B-5: The host removes the permission after receiving the byte.
ACK Software Protocol
The ACK software protocol must be used by hosts that are not designed to use the
RTS/CTS hardware protocol.
The host must send the ACK_MODE command to the imager, before any other
command, to activate the ACK software protocol. This deactivates the default
RTS/CTS hardware protocol.
When in ACK mode, the imager sends a byte then waits for an ACK character
(0x06) from the host before sending the next byte. This acknowledge tells the
imager that the byte has been correctly received by the host. Using this protocol
helps to avoid losing characters when the host is busy. The imager does not
continue sending data unless it has received the ACK character from the host.
Host TXD
to imager
RXD
Imager RTS
to host
CTS
Host RTS
to imager
CTS
Imager TXD
to host
RXD
A
B-1
B-2
B-3
B-4
B-5