When the downstream machine module cannot receive the product flow, the upstream machine is required to hold the transfer of product to the downstream machine module.
The Variable DownstreamHeld is True when the corresponding Variable UpstreamHold (see 22.214.171.124) in the connected MaterialLoadingPoint is True. The connection is made by the FlowsTo Reference.
The underlying system shall interlock the product flow of the MaterialOutput Object accordingly.
The Variable DownstreamHeld is intended to be used with OPC UA Time Sensitive Networks.