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Communication Errors are almost always caused by some type of mismatch between
the address specified in the HMI and the Data Table in the PLC. Common problems
are:
An object in the HMI is configured to read N7:250, but the N7 data file in the
PLC is configured only up to N7:200.
An object in the HMI is configured to read the preset of timer T10:0, but data
file 10 is defined in the PLC as something other than a Timer.
An object in the HMI is configured to read a Floating Point value, but the
specified data file is configured as something other than Floating Point. The
inverse of this is also true.
An object in the HMI is configured to read a bit, but the HMI object does not
properly specify leading zeros. For example
To read bit B3:5.7:
Device Type B3, address 57 (incorrect)
Device Type B3, address 507 (correct)
To read bit N12:35.3:
Device Type NfnBit, address 12353 (incorrect)
Device Type NfnBit, address 123503 (incorrect)
Device Type B3, address 1203503 (correct)
Communication Retries
When the HMI experiences a communication error, it will try to restart comms with
the PLC. This will always cause the HMI to obtain a new Connection ID from the
HMI. In some cases, it may be desirable to reduce the Inactivity Timeout setting in
the PLC so that the PLC will close any inactive connections sooner.
Phone: 425/745-3229 • Fax: 425/745-3429 • Email: support@maplesystems.com • www.maplesystems.com
1036-0175
Page 6 of 6
Rev. 01, 03/04/2011
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