Checking for RPC Methods
Before attempting to invoke an RPC method, it’s helpful to confirm whether a PLC symbol supports RPC functionality. Both DynamicInterfaceInstance
and DynamicStructInstance
classes include an HasRpcMethods
property, which returns true
if RPC methods are available for the symbol. Checking this property can help you avoid errors from attempting to call unsupported methods.
Here’s how you can check if a function block or interface has RPC methods:
var formatYesNoResponse = (bool answer) => answer ? "Yes" : "No";
Console.WriteLine
(
$"Does {MAIN.fbValue.InstancePath} have RPC methods?: " +
formatYesNoResponse(MAIN.fbValue.HasRpcMethods)
);
Console.WriteLine
(
$"Does {MAIN.ipValue.InstancePath} have RPC methods?: " +
formatYesNoResponse(MAIN.ipValue.HasRpcMethods)
);
In this example, the HasRpcMethods
property provides a straightforward way to determine whether a given symbol, such as fbValue
or ipValue
, supports RPC calls. If HasRpcMethods
returns true
, you can proceed with further steps, such as listing and invoking available RPC methods.