9XTend
‐
NEMA™
RS
‐
232/485
RF
Modem
–
Product
Manual
v2.x4x
[2007.01.04]
©
2007
MaxStream,
Inc.,
Confidential
&
Proprietary
‐
All
Rights
Reserved
41
RN (Delay Slots) Command
<Networking & Security> The RN command is
used to set/read the time delay that the transmit-
ting RF modem inserts before attempting to
resend a packet. If the transmitting modem fails
to receive an acknowledgement after sending a
packet, it inserts a random number of delay slots
(ranging from 0 to (RN minus 1)) before attempt-
ing to resend the packet. Each delay slot is 5
msec (when BR=1) and 54 msec (when BR=0).
If two modems attempt to transmit at the same
time, the random time delay after packet failure allows only one modem to transmit the packet
successfully; while the other modem waits until the channel available for RF transmission.
RN Command is only applicable if retries have been enabled [RR (Retries) Command] or if forced
delays will be inserted into a transmission [TT (Streaming Limit) Command].
RO (Packetization Timeout) Command
<Serial Interfacing> The RO command is used to
set/read the Packetization Timeout setting. RF
transmission begins when data is in the DI buffer
and either of the following criteria are met:
• RO character times of silence on the UART
receive lines (after receiving at least 1 byte)
• RB characters have been received by the
UART
RB and RO criteria only apply to the first packet of
a multi-packet transmission. If data remains in
the DI Buffer (UART receive) after the first packet, transmissions will continue in a streaming man-
ner until there is no data left in the DI Buffer.
When RO is the transmission-beginning criteria: The actual time between the reception of
the last character from the UART and the beginning of RF transmission will be at least 800 µsec
longer than the actual RO time to allow for transmission setup. Additionally, it is subject to 100-
200 µsec of additional uncertainty, which could be significant for small values of RO at high UART
bit rates.
The correct UART character time (10, 11, or 12 bits) is calculated based on the following criteria:
• 1 start bit
• 8 data bits
• 0 or 1 parity bit [as determined by the NB (Parity) Command)
• 1 or 2 stop bits [as determined by SB (Stop Bits) Command]
AT Command: ATRN
Binary Command: 0x19 (25 decimal)
Parameter Range: 0 - 0xFF [38 ms slots]
Default Parameter Value: 0
(no delay slots inserted)
Number of bytes returned: 1
Related Commands: RR (Retries), TT
(Streaming Limit)
AT Command: ATRO
Binary Command: 0x21 (33 decimal)
Parameter Range: 0 - 0xFFFF
[ x UART character times ]
Default Parameter Value: 3
Number of bytes returned: 2
Related Commands: RB (Packetization
Threshold)
