MVI69-MCM - Slave Status information
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cepha
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Wednesday 08 February 2006 2:07:50 am |
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MVI69-MCM - Slave Status information
I am trying to retrieve the status of the Modbus slaves connected to port 1 of the MVI69-MVM module. Port 1 is configured as a Master and is correctly collecting data registers from the slaves. To retrieve the status block I am setting a value of 3002 in the output word (Local:1 .Data[0]) but the module only returns blocks 0, 1 and 2.
I am using all the sample code so this should work but I am having no success in getting the status. Any help gratefully received
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jsanders
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Monday 15 May 2006 3:15:42 pm |
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RE:MVI69-MCM - Slave Status information
The Slave Status table name is somewhat misleading. It is not the best information to monitor for health of communicatons to slave devices attached to our Master Port.
Instead of the Slave Status table, try monitoring the Master Command Error List. In the port configuration, there is a tag call CmdErrPtr. This tag allows you to send the Command Error List to an area of the module which can then be brought into the ReadData array and monitored by ladder logic.
Each word in this table will show the status of each command as it executes. If the value for a command is "0", the command was successful. If any value other than zero is seen, that indicates a communication failure of that command to that node. This is a much better indication of whether or not our Master can communicate with any given slave.
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