In order for ERPConnect Services to utilize a custom function module (e.g. Z_XTRACT_IS_TABLE) instead of the standard SAP function module to avoid restrictions by reading SAP tables, you will use the CustomFunction property of the ExecuteTableQuerySettings class.

Click to open C# example.
ERPConnectServiceClient client = new ERPConnectServiceClient();
DataTable dt = client.ExecuteTableQuery("VBAK",
new ExecuteTableQuerySettings {
CustomFunction = "Z_XTRACT_IS_TABLE"
RowCount = 10

Table Restrictions

In the section Table restrictions you can find more information about the restrictions and how to install the custom function module Z_XTRACT_IS_TABLE to avoid them.