User Manual EPT USB To Serial 1 Meter Cable
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7
Troubleshooting
7.1
Hardware
Cables are the most common sources of trouble with external devices.
Check the following:
USB cable is properly inserted
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Computer power is ON
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Computer is not in Sleep or Standby
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If a USB Hub is used, be sure it is set for “Self-Powered” operation
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If a USB Hub is used, be sure all cables are properly inserted
RS232 cables – check the following:
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Output signals (TXD, RTS, DTR) are connected to the respective inputs (RXD,
CTS, DSR) in each direction.
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Check for specific handshake requirements of your RS232 peripheral.
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If handshake signals are not used, ensure the application is set to “No Hardware
Handshake”, or equivalent.
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Test the port with a loop-back connector. Connect TXD to RXD, RTS to CTS and
DTR to DSR. Use HyperSerialPort to check that data is transmitted and received.
7.2
Device Driver
Ensure the latest device driver is in use. See www.earthpeopletechnology.com/resources/drivers
If other devices with FTDI chips are installed in the system, check with all manufacturers of
these devices for the latest device drivers.
See the FTDI installation guides for additional details:
http://ftdichip.com/Documents/InstallGuides.htm
Common Windows Device Driver Troubles:
DEVICE TIMES OUT: The default settings of the device driver assume typical data transfers
of hundred to thousands or more bytes at a given time. Some applications, such as a GPS
device, only send data in short packets, often only a few bytes. If this is the case, it may be
necessary to adjust the drivers buffer size and/or latency timer to smaller values. These
values can be adjusted through the Advanced driver options as noted in Figure 2.13. The
buffer size can be reduced to 64 bytes. The latency timer can be set as low as 2ms. A setting
of 1ms will cause unnecessary USB traffic and could adversely affect data transmission.