M&M
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EFRIGERATION
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. C-11
Appendix C: Software Interface Description
DF1 Protocol Description
All DF1 transactions will be performed with the M&M controller acting as a Slave unit on
the network (peer-to-peer communications are not supported). All messages are termi-
nated with a one-byte BCC checksum character. Transaction numbers, and message
polling are required (read message responses will not return data without a poll com-
mand). Extended address fields and error messages are supported. Message blocks
may be sent with or without the multi-drop message header (half and full duplex modes
are supported).
The default software configuration for DF1 communications is shown below. Where a
parameter can be changed, a range of options is also shown. It is the responsibility of the
user to ensure that the software configuration is the same for the master and all slave con-
trollers.
• Baud rate: 9600 bps (2400/4800/9600/19200)
• Data bits: 8 (7/8)
• Parity: None (None/Odd/Even)
• Stop bits: 1 (1/2)
Currently there are four DF1 message types supported by the M&M protocol:
• Protected Typed Logical Read with Three Address Fields: (CMD 0x0F, FNC 0xA2)
• Protected Typed Logical Write with Three Address Fields: (CMD 0x0F, FNC 0xAA)
• Word Range Read (read block): (CMD 0x0F, FNC 0x01, ASCII Addressing only).
• Word Range Write (write block): (CMD 0x0F, FNC 0x00, ASCII Addressing only).
Other DF1 message types may become available later or if the need arises. A brief
description of the format for each function code will be provided below. However, for a
more thorough explanation, please refer to the Allen-Bradley DF1 Protocol and Command
Set (1770-6.5.16).
Protected Typed Logical Read
The registers within the Status Message, Control Message, and Setpoint Messages
may be read individually or in blocks. The master is responsible for setting the correct
element number and byte size for the message block.
Command 0x0F
Function Code 0xA2
Byte Size 0x02 - 0x50
File Number 0x0A-0x0D (N10-N13)
File Type 0x89 (Integer)
Element Number 0x00 - 0x27
Sub-Element Number 0x00
Checksum BCC
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