9XTend
‐
NEMA™
RS
‐
232/485
RF
Modem
–
Product
Manual
v2.x4x
[2007.01.04]
©
2007
MaxStream,
Inc.,
Confidential
&
Proprietary
‐
All
Rights
Reserved
42
RP (RSSI PWM Timer) Command
<Diagnostics> RP Command is used to enable a
PWM ("Pulse Width Modulation") output on the
Config/RSSI pin (pin 11 of the OEM RF Module).
The pin is calibrated to show the difference
between received signal strength and the sensi-
tivity level of the RF modem. PWM pulses vary
from zero to 95 percent. Zero percent means the
received RF signal is at or below the published
sensitivity level of the modem.
The following table shows dB levels above sensitivity and PWM values (The total time period of the
PWM output is 8.32 ms. PWM output consists of 40 steps and therefore the minimum step size is
0.208 ms.):
A non-zero value defines the time that PWM output is active with the RSSI value of the last
received RF packet. After the set time when no RF packets are received, PWM output is set low (0
percent PWM) until another RF packet is received. PWM output is also set low at power-up. A
parameter value of 0xFF permanently enables PWM output and always reflects the value of the last
received RF packet.
The Config/RSSI pin is shared between PWM output and Config input. When the modem is pow-
ered, the Config pin is an input. During the power-up sequence, if RP parameter is a non-zero
value, the Config pin is configured as an output and set low until the first RF packet is received.
With a non-zero RP parameter, the Config pin is an input for RP ms after power up.
RR (Retries) Command
<Networking & Security> The RR command is
used to set/read the maximum number of retries
sent for a given RF packet. When RR Command is
enabled (RR>0), RF packet retries and ACKs
(acknowledgements) are enabled.
Exceptions: If the MT command in enabled
(MT>0) or if a broadcast Destination Address is
used (DT = 0xFFFF); RF packet retries and ACKs are disabled.
After transmitting a packet, the transmitting RF modem waits to receive an acknowledgement
from a receiving modem. If the acknowledgement is not received in the period of time specified by
RN (Delay Slots) Command, the original packet is transmitted again. The RF packet is transmitted
repeatedly until an acknowledgement is received or until the packet is sent RR times.
Table
4
‐
04. PWM
Values
dBm above sensitivity
PWM percentage
(high period / total period)
10
20%
20
35%
30
50%
AT Command: ATRP
Binary Command: 0x22 (34 decimal)
Parameter Range: 0 - 0xFF
[x 100 milliseconds]
Default Parameter Value: 0x20 (32d)
Number of bytes returned: 1
AT Command: ATRR
Binary Command: 0x18 (24 decimal)
Parameter Range: 0 - 0xFF
Default Parameter Value: 0x0A (10 decimal)
Number of bytes returned: 1
