The manual has the user using hyperterminal to send a text-file with the contents of + in it. I think the escape is just +, not +++. Also, you have to wait a few seconds (two is default) of no serial activity before the escape character will work.
I'm not sure if sending a text-file causes the terminal to behave differently then just typing +, or +++, but it might be worth trying. Maybe it needs basically no delay between the three +++, or it does something else (if the escape char is just +)
Also, have you checked that your signals are not inverted? Maybe the usb-serial is defaulting to normally high, and the module wants normally-low, or vice-versa.
Confirmed in comments below as three + characters, or +++. You have to send it as a text file. I suspect that feeding hyperterminal a text file causes the three bytes to be sent as close to each other as possible, while typing them manually causes a ~200ms+ inter-character delay (e.g. as fast as you can manually hit the + key).
Apparently the device has a much shorter "enter AT control mode" timeout them other similar devices, (like xBees, or such).
You can consider HALT/HASS tests on how robust the communication network is.
Conisder Fault injection to test high level and low level responses with various levels and frequencies of noise ingress required to cause error by radiated or conducted noise sources.
- fault detection, recovery, logging, fault isolation
- Conducted noise on AC DC and comm channel lines.
- Radiated power line transient (PLT) pulses, nearby cable transients pulses or radiated ESD impulse noise from a metal plane antenna using HV discharge with rep. rate.
- margin tests on power supply voltage, thermal stress, random vibration or pulsed vibrating tool
- stalled rotor tests
- consider worst case data patterns if any, scope end to end channel for margin.
BER is directly related to SNR. Ideal channel is expected to be error free, but in reality can you guarantee ideal SNR? Is a pure digital signal or is ingress possible?
I have often made false assumptions in my past communication channel designs in the 70's and learnt my lesson.. Never assume and test margin for HALT HASS to failure and find weakest links.
Best Answer
Roving Networks offers the RN-131C and RN-131G for $45/$40 WiFi - UART. It uses 100 mA when awake, and 10 uA asleep. I'm using a related system on a project and it works quite well. The C variant is commercial temp range, the G is industrial. I think they have RS-232 as well as SPI/I2C versions as well. I'm not sure if this is the WiFly GSX you mentioned in your original question.
Also, we looked at the modules from Redpine Signals. I'm not sure what their power consumption is, but the Connect-i-on series of products has the other functionality you're looking for.