Is the description of communication wrong?


#1

For incoming communication on controller COM ports, which is requested by another device, the flowchart must first use Listen for Incoming Communication and then use Accept Incoming Communication to establish a connection.

For incoming communication on serial modules, which is requested by another device, the flowchart uses the Open Outgoing Communication and Communication Open? commands to establish a connection.

This is the description in the 264th page of the user’s Guide (PAC Control User s Guide). Is this description wrong?


#2

No. It is not wrong.

Think of it in terms of ‘smart’ and ‘dumb’.
A smart device can start the process, a dumb device can only respond to data, it can not start a conversation.

In the first part of page 264, it is a smart device, so the PAC can listen and accept.
The second part is a description of a dumb device so the PAC opens outgoing communications and checks that has occurred OK.


#3

The above descriptions are based on the IP-addressable serial module and do not apply to the serial port at the top of the controller, right?


#4

The listen/accept requirement only applies to “tcp:” comm handles. Using Ben’s analogy, the tcp protocol is smarter/more complicated than any of the other types of comm handles we support, which are okay w/just the 1 “open” step.

It’s unfortunate that open command has the “Outgoing” word in there since that’s a bit confusing, since you could use that comm handle strictly for incoming data.