Show Bid Request Serial Communication Protocol Bid Request Id: 11248 Bookmark in my 'To Do' list Posted by: VB_HELP (3 ratings) (Software buyer rating 10) Non-action Ratio: Very Good - 0.00% Buyer Security Verifications: Good Approved on: Mar 19, 2002 3:52:04 PM EDT Bidding Closes: Apr 2, 2002 4:02:39 PM EDT Viewed (by coders): 325 times Deadline: 3/22/2002 TIME EXPIRED Phase: 100% of work completed and accepted. Coder has been paid. Max Accepted Bid: Bidding is closed Project Type: Personal Project / Homework Help Bidding Type: Open Auction Categories: Visual Basic Enter chat room for this bid request (0 active users at Sep 19, 2003 7:25:05 AM EDT) Description: The following is the protocol I need to have designed in a Visual Basic Class/Classes and two forms (one form will be the Server, the other will be the Client): Communication Protocol: Messaging between the servers is bi-directional (either side may initiate). An ENQ/ACK-NAK protocol is employed wherein the sender first transmits an enque (ENQ) to bid for the line and must receive an ACK response to the ENQ before actually transmitting the data message. Line bid collisions (simultaneous ENQ's by both sides) are resolved in favor of the Server. Server will ignore an ENQ received from Client when Server has a line bid (sent ENQ) outstanding. Client will always ACK Server's ENQ and will relinquish its line bid if it is waiting for an ACK to its ENQ. All messages are of the format <STX> message data <ETX> <bcc> where <bcc> (block check character) is the one-character 'exclusive or' of all characters in the message following (but not including) STX through and including ETX. ACK/NAK response to received messages (not to ENQ) is returned according to block check validity without regard to message format or content. There is no provision in the protocol or message set definition for reporting or responding to received data that is found to be erroneous or invalid. A NAK response to a received message is returned ONLY on failure of the bcc calculation. There is defined within Client a logical status reflecting a basic property of the interface known as 'link up'/'link down'. This property is considered to indicate internally to the Server that the Client is/is not communicating with the link established. On interface startup, link down status is assumed. The Server protocol manager will not attempt to send any queued message to the Client except 'Start Transmission' (record-id "08", message "STARTRAN"). The 'link up' status occurs when and only when the protocol manager has received an ACK response to a 'Start Transmission' message. The 'link down' condition occurs when: the interface is first 'started'; three successive NAK's are received from the Client; three 'response timeout's' occur to a message sent to the Client (maximum response time for receipt of ACK is 3 seconds when 'link up', 30 seconds when 'link down'); or when an ACK is received in response to a 'Stop Transmission' (record-id "07", message "STOPTRAN") Deliverables: Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. Complete copyrights to all work purchased. Platform: Windows 98, Windows NT 4.0 SP3 Must be 100% finished and received by buyer on: Mar 22, 2002 EDT Deadline legal notes: All times are expressed in the time zone of the site EDT (UT - 5). If the buyer omitted a time, then the deadline is 11:59:59 PM EDT on the indicated date. Special Conditions / Other: I need to present this project before or on march 22, so every help will be appreciate and compensate. Remember that contacting the other party outside of the site (by email, phone, etc.) on all business projects < $500 (before the buyer's money is escrowed) is a violation of both the software buyer and seller agreements. We monitor all site activity for such violations and can instantly expel transgressers on the spot, so we thank you in advance for your cooperation. If you notice a violation please help out the site and report it. Thanks for your help.   Bidding/Comments: All monetary amounts on the site are in United States dollars. Rent a Coder is a closed auction, so coders can only see their own bids and comments. Buyers can view every posting made on their bid requests. See all rejected bids (and all comments) Name   Bid Amount    Date   Coder Rating   Royce3 (11 ratings) in Houston, Texas United States Bid id: 127,067   N/A Mar 19, 2002 4:22:18 PM EDT  10 (Excellent)     This protocol you describe sounds very similar to the DirectNet protocol. I'm a professional industrial software engineer, and have been programming for over 10 years. I can do this for you, but not by the required date you have requested. *IF* you can change that to the 24th or 25th, I would be happy to do it for you.           There are 15 private replies to/from Royce3. Click here to view them.