CCM, DirectNet, HAP

[jaRobert]

I am new to the directlogic PLCs and ECOM and I am having some trouble understanding the relation between the protocols.  My understanding so far is that HAP is a wrapper around the DirectNet Protocol (also called CCM protocol?), but I cannot find a solid HAP protocol reference that describes what exactly each byte in the protocol does (such as Function 22 is response, Function 23 is ...) or if such a resource even exists.  I've seen a lot of wireshark traffic that does not seem to fit perfectly into my understanding of HAP or DirectNet, which makes me think that there is a spec I'm missing.  Also, the Ethernet Spec and the DirectNET manual have a lot of great information, but I don't think there is much about the HAP stuff.  So, what is the relation between HAP and DirectNet, what is each used for, and are there any complete specs that tell us how to disect the HAP?

Thanks!
jr

[BobO]

HAP is Host's proprietary messaging and configuration layer that sits on top of UDP, IPX, and some others, and implements our basic Ethernet behaviors. It has bunches of function codes, including codes for CCM (DirectNet), K Sequence, and our new MX controller protocol. Those codes essentially allow us to package up a CCM request and send it over HAP to a waiting PLC, who processes the CCM request, and returns the response via HAP.

In general it isn't necessary to know HAP...just use our interface library. It's free, it works (it's what we use), and if you need the source, we've even been known to provide it to folks that ask. Although unless you plan on porting it, just use the DLL...much simpler.

I'm actually at ADC right now, but I'm sure one of the other guys back at the ranch can help you.