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Chapter 4: Network Topologies
Example: You have a system with 5 remotes and 1 master as shown below:
Slave 22
UA = 22
Slave 7
UA = 7
Slave 2
UA = 2
Slave 11
UA = 11
Slave 5
UA = 5
Master
UA = 1
Figure 4-6. Sample system configuration.
The Master collects data from Remote 2, 11, 5, 7, and 22. Remote 5 contains GPS data, you want this data to be updated more
frequently than the data from the other units. You also need to send correction data three times per frame to ensure accurate
readings. Your TDMA table may look something like this:
TDMA Table
UA,
// Position
1,
// 1
5,
// 2
2,
// 3
11,
// 4
1,
// 5
5,
// 6
7,
// 7
22,
// 8
1,
// 9
5,
// 10
The Max. packet size of the remotes, S212 on master = 100 bytes.
The Max. Packet size of the Master’s data to the remotes, S112 on master = 200 bytes.
Using the formula given above:
T_tdma_table(10) = 2.3076 + (0.0684 * 10) = 2.9916
T_data_packet_Master(200) = 1.9327 + (0.0673 * 200) = 15.3927
T_data_packet_Slave(100) = 1.9327 + (0.0673 * 100) = 8.6627
T_total = 2.9916 + 15.3927*3 + 8.6627*7
T_total = 2.9916 + 46.1781 + 60.6389
T_total = 109.8086
The entire TDMA frame will take just under 110 ms.
In addition to the settings required to configure a PMP network, additional registers must be set to define the Fast TDMA
parameters of operation:
S244: Channel Request Mode = 2 Selects fast TDMA mode. Must be set on master and remotes.
S112: Packet Max Size—Determines the maximum data packet size of the user data from the Master, so the duration of the
master data slot can be different for master and slaves.
