TS4000 Radio Modem User’s Manual
AirNet Packet Protocol
48
Configuration Parameter
Setting
CSMA MAC Setup: Data Pkts: Min Idle Slots
3
CSMA MAC Setup: Relay Pkts: Min Idle Slots
1
Store and Forward Repeater Operation: All Packets
Relay All
Repeater C Site
Modem Address: Individual
4
CSMA MAC Setup: Data Pkts: Min Idle Slots
3
CSMA MAC Setup: Relay Pkts: Min Idle Slots
2
Store and Forward Repeater Operation: All Packets
Relay All
Remote Sites
Modem Address: Individual
10+
(each remote must have a
unique address)
CSMA MAC Setup: Data Pkts: Min Idle Slots
Number of slots for an outbound
polling packet
Number of slots for an outbound polling packet = Packet Transmit Time / Slot Time + Largest
Relay Pkt: Min Idle Slot
Packet Transmit Time = [9 * Max Outbound Message Length (in bytes) * Overhead / Air Rate
(in kbps)] + Radio Tx Attack Time (in ms)
Overhead = 1 if Coding (FEC) is Unchecked
Overhead = 1.5 if Coding (FEC) is Checked
Slot Time = 1.5 * Radio Transmit Attack Time
Example:
Max Message Length for Modbus protocol = 255 bytes
Radio Tx Attack Time = 20ms
(this value can be read on the Radio Hardware Screen)
Air Rate = 9.6 kbps
(this is configured on the Radio tab)
Coding = Unchecked
(this is configured on the Radio tab)
Largest Relay Pkt: Min Idle Slots = Repeater C: Relay Pkts: Min Idle Slots = 2
Slot Time = 1.5 * 20ms = 30ms
(this is configured on the Packet General tab)
Packet Transmit Time = [9 * 255 * 1 / 9.6] + 20 = 259ms
Number of slot for an outbound polling packet = 259/30 + 2 = 11 (rounded up from 10.6)
(this value must always be round up)