TS4000 Radio Modem User’s Manual AirNet Packet Protocol 46
Configuration Parameter Setting
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 B: Relay Pkts: Min Idle Slots = 1
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 + 1 = 10 (rounded up from 9.6) (this value
must always be round up)
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