Smart PA Modbus

Modbus Pre-Capture Filters and Post-Capture Filters

You would define device for two purposes. One is to define function codes and their data type and second is to define filters. Function code describes how to interpret a range of registers. Where as filter defines which packet to capture, and which to ignore. Device are of two types. Generic and specific. Specific device define function codes and filters which are specific to a particular modbus address, where as Generic device defines the same for any modbus device whose specific definition is not present. If all devices have same register mappings, you can define a single generic device for all of them. If the devices have different register mappings, you can define specific devices for each. You can define multiple specific devices, but there can be only one generic device. The rule is if a specific definition for a device is present, it will be used, otherwise if generic device is present, its definition is applied. If none of them are present, a default hard coded definition is used. If you do not define any device, the packets will still be captured. However the register mapping and data type mapping may not match your field device. You can either define these settings using following dialogs, or you can used the data watch  tools to convert specific hex bytes to a specific data type.

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