Rockwell Automation D17846.2.4 CONTROLNET KT EMULA - Manual (Page 24)

Publication 1784-6.2.4 - September 1997
3-4 How Your Driver Operates the KTCX Card
Send Mailbox The dual-port’s send mailbox (bytes: 0082h - :047Fh) can hold up to
1021 bytes. However, you must refer to the DF1 Protocol and
Command Set (Pub. 1770-6.5.16) for the exact size requirements of
packets for each message type. As you develop your driver, you
should refer to the following items in this section:
• Procedure for Sending Data to the KTCX Send Box
• Send Data Packets Examples
• Send Data Memory Map
Procedure for Sending Data to the KTCX Send Mailbox
To send a packet to the Send Box in the KTCX:
1. Verify that the ACCESS byte is 01h.
2. Verify that the VALID byte is 01h.
3. Transfer the message or command packet into the send mailbox.
4. Send the packet by writing 00h to VALID.
5. Write 00h to ACCESS flag.
Now the card is aware of the message packet.
Send Packet Examples
Refer to the following examples as you develop the send packet por-
tion of your driver.
Send Packet Procedure #1: Diagnostic Status.
The following steps describe a typical procedure for sending a packet
requesting diagnostic status.
1. The host application builds a Diagnostic Status command packet
in a buffer.
2. The host polls the Send Access Request byte (0080h)
3. Host polls the Send Data Valid byte (0081h). If the values of
0080h and 0081h are 01h then the host proceeds.
4. The host places the Diagnostic Status packet into the mailbox
beginning at location :0082h.
5. The host zeros the Send Data Valid and Send Access Request
bytes.
!
ATTENTION: Failure to execute the following steps
can cause your card to behave improperly and cause
damage to your system.