T2: Unit Transmits Response To Host; T3: Host Acknowledges Unit Response; Ae Bus Communications Transaction Example - Advanced Energy Paramount MF 2 kW User Manual

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Advanced Energy
a message addressed to it. If the address matches but the exclusive-or (XOR)
sum of the bytes in the packet (including the checksum) is not zero, the
Paramount MF 2 kW unit sends a negative acknowledgment (NAK),
hexadecimal 15h, to the host computer.
• If the address matches and the message is intact, the Paramount MF 2 kW unit
sends an acknowledgment (ACK), hexadecimal 06h, to the host computer.
If the Paramount MF 2 kW unit receives a request for data or status information, it
gathers and sends the requested information. Otherwise, it evaluates the incoming
command and sends a message packet that contains a 1-byte data value (CSR code)
to the host. The power supply sends CSR code 0 when it has accepted the command.
If the host computer receives a NAK from the Paramount MF 2 kW unit, the host
computer either retransmits the packet or does whatever else it has been programmed
to do in this situation. If the host computer receives an ACK, it waits for the
requested data or status information, or it waits for the CSR code telling it whether or
not the new parameter was accepted. If the host computer receives no response
within a reasonable period, it takes whatever action it has been programmed to take.
T : UNIT TRANSMITS RESPONSE TO HOST
2
The Paramount MF 2 kW unit prepares a response packet with the requested
information or appropriate CSR code, which it then transmits to the host computer.
The host computer then determines, by means of the checksum, if the response
packet is complete. If the host computer detects an error in the transmission (the
checksum is not validated), it can request the packet be sent again by transmitting a
NAK.
T : HOST ACKNOWLEDGES UNIT RESPONSE
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If the Paramount MF 2 kW unit receives an ACK from the host computer, it returns
to the normal waiting state. If the Paramount MF 2 kW unit receives a NAK from the
host computer, the unit retransmits the response packet. The Paramount MF 2 kW
unit continues to retransmit in response to NAK transmissions until the host
computer stops the cycle. If the Paramount MF 2 kW unit receives no response, it
assumes an ACK and returns to the waiting state.

AE BUS COMMUNICATIONS TRANSACTION EXAMPLE

Figure 4‑17
host computer and the Paramount MF 2 kW unit.
57020114-00E
illustrates the steps in an example communications transaction between a
Communication Controls
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Paramount MF 2 kW Generator
4‑18