To optimize data throughput between clients and the DataHub, custom clients can make two calls:

msgformat is one of:

DH_SetTransmitFormat instructs the API to transmit all point change messages from the custom client to the DataHub using the specified message format.

DH_SetReceiveFormat instructs the DataHub to transmit all messages to the custom client using the specified format. This call will fail with ST_NO_TASK if the custom client has never successfully called one of DH_RegisterPoint, DH_RegisterExistingPoint or DH_RegisterAllPoints. This is because the Cascade DataHub does not maintain internal state information for clients that are not registered to receive point exceptions.