ZETRON 640 DAPT XTRA, Installation And Repair Manual

Page: 144 / 210

Troubleshooting and Repair
132 025-9416
Example Valid Entries Description
5C 2 hex digits
01 - FF Packet serial number - differentiates between redundant and
original packets
Data Block Elements
The data block is of variable length. Recall that several data blocks can be included in one
packet. Each block must end with an ETB (end of text block) character and the last block must
end with an ETX (end of text) character. The block format depends on whether the TNPP format
is capcode or ID paging.
The data block structure for an ID page is shown in Figure 66.
Identifier
(10)
Block
type
(1)
Function
code
(1)
Message text
(N)
End
flag
(1)
Figure 66. Data Block Structure for an ID Page
The data block structure for a capcode page is shown in Figure 67.
Capcode
(8)
RF
zone
(1)
Function
code
(1)
Message text
(N)
End
flag
(1)
RF
channel
(1)
Page
class
(1)
Page
type
(1)
Block
type
(1)
Figure 67. Data Block Structure for a Capcode Page
Table 25 describes each data block element and the possible values. Note that the shading in each
row identifies whether the fields are used in a capcode page (no shading), an ID page (light
grey), or both (dark grey). The “Example” column shows the elements in the example packet on
page 131, where applicable.
Redundant Packets
In simplex systems, the originating encoder is not aware of errors and should transmit the packet
multiple times. TNPP has serial numbers on all packets so the redundant packets are ignored by
the Model 640 if they have already been received and processed without error. If reliable data
circuits are used, this retransmission procedure may not be necessary.
Table 25. Explanation of TNPP Packet Data Block Characters
Example Valid Entries Description
A
A = full capcode page
B = ID page
Block type flag
G G = Golay
P = 512 baud POCSAG
p = 1200 baud POCSAG
Q = 2400 baud POCSAG
2 = 2-tone 5 = 5/6-tone
H = HSC N = NEC D3
B = Blick M = Multitone Page type (format)