A couple of things you could try:

  1. Check/configure the port using the MODE command. 
    C:> mode com1

Status for device COM1:
-----------------------
    Baud:            1200
    Parity:          None
    Data Bits:       7
    Stop Bits:       1
    Timeout:         OFF
    XON/XOFF:        OFF
    CTS handshaking: OFF
    DSR handshaking: OFF
    DSR sensitivity: OFF
    DTR circuit:     ON
    RTS circuit:     ON

c:> help mode
Configures system devices.

Serial port:       MODE COMm[:] [BAUD=b] [PARITY=p] [DATA=d] [STOP=s]
                                [to=on|off] [xon=on|off] [odsr=on|off]
                                [octs=on|off] [dtr=on|off|hs]
                                [rts=on|off|hs|tg] [idsr=on|off]

Device Status:     MODE [device] [/STATUS]
...

    [download]
  2. Then you can isolate whether it is perl or the module or the port configuration by driving the port manually.

    Write the command sequence into a file using a (binary capable) editor. Then send that sequence to the device: copy file.bin /b comN: /b

    Then retrieve the response using the same technique: copy comN/b response.bin /b. Then you can check the file to see what you get.

    By configuring the port using mode, you can start with a slow transmission rate (say 1200), and whatever handshaking (rts=on or xon=on) until you get reliable transmission. Then slowly ramp the baud rate until it starts to fail or you reach the maximum.

    Once you've figured out what the device is capable of, you can automate the process using the module .

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re^3: Win32:SerialPort not reading all characters by BrowserUk
in thread Win32:SerialPort not reading all characters by sxmwb

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