7-32
Transmission Sequence
• Transmission protocol
• In case of RS232
Host
MINAS-A6
Receiving
data
Transmitting
data
1) ENQ(05h)
2) EOT(04h)
3) Data block
4) ACK(06h)
(or NAK (15h))
5) ENQ(05h)
6) EOT(04h)
7) Data block
8) ACK(06h)
(or NAK (15h))
• In case of RS485
Host
Module ID : 0
1) 81h, ENQ (05h)
2) 81h, EOT (04h)
3) Data block
4) ACK (06h)
(or NAK (15h))
5) 80h, ENQ (05h)
6) 80h, EOT (04h)
7) Data block
8) ACK (06h)
(or NAK (15h))
MINAS-A6
Module ID : 1
Receiving
data
Transmitting
data
• Line control
Decides the direction of transmission and solves the contention.
Reception mode... From when the module (host or driver) returns EOT after receiving ENQ.
Transmission mode... From when the module (host or driver) receives EOT after trans-
mitting ENQ.
At contention of transmission and reception... Slave side will enter to reception mode
when it receives ENQ while waiting for EOT after transmitting ENQ, by giving priority
to ENQ (of master side).
• Transmission control
On entering to transmission mode, the module transmits the command block continu-
ously and then waits for ACK reception. Transmission completes at reception of ACK..
ACK may not be returned at transmission failure of command byte counts. If no ACK
is received within T2 period, or other code than NAK or ACK is received, sequence will
be retried. Retry will start from ENQ.
• Reception control
On entering to reception mode, the module receives the transmitted block continuously. It
will receive the command byte counts from the first byte, and continuously receive extra 3
bytes. It will return ACK when the received data sum becomes 0, by taking this status as
normal. In case of a check sum error or a timeout between characters, it will return NAK.
4. Communication
Specifications
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