Paradise Datacom 205486 REV F, Руководство по эксплуатации

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Operations Manual, HPA2, Compact Outdoor SSPA 208495 REV B 113
11.1 Serial communication
This section describes the normal communication protocol between the CO SSPA and a host
computer over RS-232/RS-485 serial interface. Serial port settings on the host computer must
be configured for 8 bit data at no parity, with 1 stop bit. The baud rate should match the
selected baud rate parameter on the SSPA unit.
Selection between the RS-232 and RS-485 interface depends on the state of pin D of the J4
M&C connector. Connect pins D and d to select RS232 interface. Otherwise SSPA will
operate in RS485 mode.
The unit will only respond to properly formatted protocol packets. The basic communication
packet is shown in
Figure 11-2 . It consists of a Header, Data, and Trailer sub-packet.
11.1.1 Header Packet
The Header packet is divided into 3 sub-packets which are the Frame Sync, Destination Ad-
dress, and Source Address packets, as shown in
Figure 11-3 .
11.1.1.1 Frame Sync Word
The Frame Sync word is a two byte field that marks the beginning of a packet. This value is
always 0xAA55. This field provides a means of designating a specific packet from others that
may exist on the same network. It also provides a mechanism for a node to synchronize to a
known point of transmission.
11.1.1.2 Destination Address
The destination address field specifies the node for which the packet is intended. It may be an
individual or broadcast address. The broadcast address is 0xFF or 0xAA (see
Section 11.1.5
Multiple Device Access
). This is used when a packet of information is intended for several
nodes on the network. The broadcast address can be used in a single device connection
when the host needs to determine the address of the amplifier. The SSPA unit will reply with
its unique address.
HEADER
(4 bytes)
DATA
(6-32 bytes)
Figure 11-2: Basic Communication Packet
TRAILER (1
byte)
HEADER
(4 bytes)
DATA
(6-32 bytes)
TRAILER (1
byte)
Frame Sync (2 bytes)
0xAA55
Destination Address
(1 byte)
Source Address
(1 byte)
Figure 11-3: Header Sub-Packet