Communications Protocol; Header; Figure 4-16. Graphic Representation Of A Message Packet - Advanced Energy Pinnacle 20 kW Manual

Advanced Energy

Communications Protocol

The AE Bus (Host) protocol uses pure binary data (nothing is coded ASCII) and is designed to
facilitate direct communications between a host computer and the Pinnacle power supply.
Five types of information (fields) make up communications message packets (see Figure 4-5):
• header (address and length of data field)
• command (see command list later in this chapter)
• optional length byte
• data
• checksum (error checking)
Figure 4-16 on page 4-50 shows the organization of these data fields in the AE Bus message
packet. The figure is followed by paragraphs that describe in detail the data fields.

Figure 4-16. Graphic representation of a message packet

HEADER

The first byte in each message packet contains two pieces of information: five bits contain the
packet address, and three bits contain the data byte count. If the message packet originates
with the host computer (master), the address specifies the packet's destination (to a Pinnacle
unit, for example). If the packet is going to the host, the address specifies the packet's origin
(from the Pinnacle unit). The address section of the Header field is five bits long, which allows
a total of 32 distinct addresses. Address 0 (zero) is reserved for the network broadcast address;
when this address is used in a host-originated packet, all units execute the packet (but do not
respond back to the host).
4-50
Page 84 of 182
®
I/O Communication and Control 5702199-A