It seems that every client that I assist in implementing HL7, we get to testing the process and we send in an ADT, ORM, ORU, or some other message and we wait for the automated acknowledment, but it never comes.

I then remember that unless I have MLLP version 1.0.308.0, and 1.0.309.0 (current) of Microsoft.solutions.btahl7.mllp.dll I better camp out for a while, while I know it states that it can take up to 10 seconds to get the ack, I have gone to lunch and come back with no response. I even heard that there is a 24 hr delay. So make sure that you have the following patches from Microsoft for the HL7 adapter.

• KB893369: HL7 Interrogative transactions may take 10 or more seconds to complete when MLLP synchronizes communications end-to-end
• KB893404: The BizTalk Accelerator for HL7 sends an acknowledgement message to the source system after a long delay

Don’t forget to follow the post installation instruction on getting the send adapter to be a solicit/response as documented here.