Rockwell Automation D17846.2.4 CONTROLNET KT EMULA - Manual (Page 29)

Publication 1784-6.2.4 - September 1997
How Your Driver Operates the KTCX Card 3-9
Receive Packet Example #2: Interrupt Method.
The following steps describe a typical procedure for receiving a
packet with an interrupt.
1. The KTCX card sets the hardware interrupt.
2. The host removes the packet from the receive mailbox.
3. The host writes 00h to byte 0481h to clear the Receive Data Valid
flag.
4. The host writes 00h to byte 0480h to clear the Receive Access
Request flag.
Receive Packet Example #3: Polled Method.
The following steps describe a typical procedure for receiving a
packet with the polled method.
1. The host monitors Receive Access Request and Receive Data
Valid flags. When both go to 01h data is available.
2. The host removes the packet from the receive mailbox.
3. The host writes 00h to byte 0481h to clear the Receive Data Valid
flag.
4. The host writes 00h to byte 0480h to clear the Receive Access
Request flag.
Receive Data Memory Map
Refer to Table 3.E to determine the use of each dual-port address as
you receive packets.
Table 3.G Receive Data Memory Map
Byte Description Function 1 Contents = Meaning
Typical Access
2
KTCX . . . . . Host
Comments
:0480h Receive Access
Request STAT 00h= KTCX control
01h= host control R/W . . . R/W This is one of the receive mailbox control bytes. Set 0481h
(Receive Data Valid) first, then set 0480h (Receive Access
Request).
:0481h Receive Data Valid STAT 00h= KTCX control
01h = host control R/W . . . . R/W This is one of the receive mailbox control bytes. The proper
order for setting them is :0481h first, then :0480h (Receive
Access Request).
:0482h Length (lo byte) PKTCX --- R . . . . . . . .W Indicates length of the mailbox data in two bytes.
:0483h Length (hi byte) PKTCX --- R . . . . .. . . W
:0484h SRC PKTCX --- R . . . . . . . W This is the originating source of the message packet.