Rockwell Automation 5370 Color CVIM Communications Manual - Manual (Page 101)

Chapter 5
Using the RS–232 Ports
5–33
The remainder of this chapter describes the Color CVIM implementation of
the DF1 protocol. After you have made the equipment connections and
configured the Color CVIM module for RS–232 communications, DF1
packets of data can be sent to the Color CVIM module.
DF1 is an Allen–Bradley developed software convention used for RS–232
communications. DF1 provides some handshaking and data–packing formats
which allow for fast communications with integrity of the data. The Color
CVIM uses only the Data Link Layer of DF1.
This chapter describes a simple application level of DF1 for communications
between a Color CVIM module and a computer host. This application level
requires that all transmitted data be preceded by a header and terminated by a
trailer and a Block Check Character (BCC). In addition, ACK / NAK
characters and simple time out conventions are used to ensure the integrity of
the data. This is called the Data Link Layer.
We do not provide a complete description of DF1 in this manual. We have
only provided the information necessary to transmit data between a host
computer and the Color CVIM module. If you want to learn more about DF1,
we suggest reading Publication 1707–6.5.16.
In the DF1 protocol mode, all data is transferred between the Color CVIM
module and a host as bytes with a value between 00(hex) and FF(hex). Refer
to Appendix E to convert control codes like ACK and NAK to/from
hexadecimal values.
DF1 Protocol
What is DF1?
DF1 Character Set