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CMC TECHNICAL REFERENCE MANUAL
1X36003 Version 2.52
1996-1999 Ingersoll-Rand Company
Date of Issue: 18-Oct-1999
When the CMC receives a DF1 command without any communication error and the
command is executed successfully, a normal response with status code 00h is returned.
If the UCM dose not receive the command due to a communication error, no response is
returned and the command initiator will eventually time out.
If the UCM dose receive the command, but detects error (invalid BCC/CRC...), control
characters DLE NAK is returned to the command initiator, which in turns retransmits the
command message and restarts a time out to wait for the response. This can be repeated a
few times depending on the limit preset for retransmission. Once the limit is exceeded, the
command initiator is informed of the failure and proceeds to the next command.
If the time out expired before a response is received, the command initiator sends out DLE
ENQ control characters to request a retransmission of the last response. It restarts a time
out and wait for the response. There is a limit on the number of inquiries allowed per
command message. When this limit is exceeded, the command initiator proceeds to the
next command.
When UCM receives DLE ENQ or DLE NAK message, it resends the last response to the
command initiator. When DLE ACK message is received by the UCM, no response is
returned.
When the UCM receives a command without any communication error, but cannot handle it,
the UCM will return an exception response with the appropriate status code informing the
command initiator of the nature of failure.
NOTE
The table below explains the meanings of different control symbols for DF1 protocol:
Control Symbol
Definition
DLE ACK
a message frame has been successfully received
DLE NAK
a message frame was not received successfully
DLE ENQ
request retransmission of a response from the destination node
Communication Parameters
Configuration of the UCM RS-422 port’s communication speed (baud rate), parity, number
of data bits, number of stop bits... is available through the Ingersoll-Rand UCM-Wizard Tool
and will be configured by a certified Ingersoll-Rand Service Representative. The settings
should be the same as the 1770-KF2 interface module.
Network Setup
The network diagram that follows depicts the communication interface between Allen-
Bradley DF1 network and Ingersoll-Rand CMC Microcontroller.
The 1770-KF2 always acts as a slave. The slave cannot initiate a command; i.e., the UCM
cannot initiate a command over DH+ network. It only returns response messages to queries
that are addressed to them individually. Broadcast is not supported over the DF1 network.