Structure Of The Slave Response - Eaton PowerXL DA1 Communications Manual

2.6.2 Structure of the slave response

2.6.2.1 Required transfer time
2.6.2.2 Normal slave response
2.6.2.3 No slave response
• The time between the moment a request is received from the master
and the variable frequency drive's/variable speed starter's response is at
least 3.5 characters (rest time).
• Once the master has received a response from the variable frequency
drive/variable speed starter, it must wait for at least the rest time before
it can send a new request.
• If the master request contains a write-register function (function code
06), the variable frequency drive/variable speed starter immediately
returns the request as a response.
• If the master request contains a read-register function (function code
03), the variable frequency drive/variable speed starter returns the read
data with the slave address and the function code as a response.
In the following cases, the variable frequency drive/variable speed starter
ignores the request and does not send a reply:
• on receiving a broadcast request.
• if the request contains a transmission error.
• If the slave address in the request does not match the variable frequency
drive's/variable speed starter's address.
• With a CRC or parity error.
• If the time interval between the messages is less than 3.5 characters.
￫
The master must be programmed to repeat the request if it
does not receive a response within a specified time.
Modbus RTU for variable frequency drive DA1, DC1, DE1 09/16 MN040018EN www.eaton.com
2 Modbus RTU
2.6 Operating mode Modbus RTU
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