In order to poll from a Siemens PLC using the S73&400 I/O server, PUT/GET access must be enabled, Optimized Block Access must be disabled for the data blocks that will be polled, and these changes must be downloaded to the PLC.
APPLICABLE PRODUCTS
- Ewon Flexy line
ISSUE / QUESTION / SYMPTOM
- Can ping and connect to Siemens PLC, but can't poll data from it
- Ewon logs show error "S74srv-Invalid DataType in read response"
POSSIBLE CAUSES / ANSWER
First, activate the the "PUT/GET communication" feature:
- Expand the PLC in the Devices tab of the project tree, then click "Device configuration"
- In the General tab, scroll down and click Protection
- At the bottom under "Connection mechanisms", check "Permit access with PUT/GET communication"
Fig 1. Adjusting the PLC's properties
Second, ensure "Optimized block access" is not checked:
- Right click the data block and go to its properties
- Navigate to Attributes under the General Tab
- Uncheck "Optimized block access"
Fig 2. Adjusting the data block's properties
Finally, download the program to the PLC to ensure these changes are applied.
ADDITIONAL INFO