FarSync Flex FAQ

What is High Speed, Full Speed and Low Speed USB?

High Speed USB is 480Mbps, Full Speed is 12Mbps and Low Speed is 1.5Mbps. FarSync Flex can run at High Speed or Full Speed.

What is the difference between USB 3.0, 2.0 and 1.1?

USB 1.1 was the first version to be widely adopted and supports 12Mbps and 1.5Mbps speeds. USB 2.0 is an enhancement to USB 1.1 and supports 480Mbps and 12Mbps speeds. USB 3.0 permits much faster speeds than USB 2.0. The Flex will work on USB 3.0, 2.0 and 1.1 but the higher line speeds will not work with USB 1.1.

What is the difference between Flex (V1), V2 & V3?

FarSync Flex (V1) was the initial product version supporting HDLC and Transparent synchronous NRZ data at up to 2.048Mbps and later asynchronous data up to 115200bps. Synchronous coded data in NRZI, FM0 and FM1 is supported at up to 1.536Mbps. Monitoring Mode was also supported. Flex (V1) later supported software BERT at rates up to 2.048Mbps (NRZ) or 1.536Mbps (Coded).

FarSync Flex V2 was the second generation hardware, supporting a super set of the synchronous NRZ data rates to 2.048Mbps, asynchronous rates to 115200bps. It added support for Manchester and Differential Manchester coding to NRZI, FM0 and FM1 at rates up to 2.048Mbps. Flex V2 uses a frequency synthesizer for clock generation, supporting hundreds of standard rates with the option to generate just about any non-standard rate too. Flex V2 added support for Terminal Timing and various other extended clocking modes. Flex V2 later added support for hardware BERT at rates up to 16Mbps (NRZ) or 10Mbps (NRZI, FM0, FM1, Manchester & Differential Manchester).

FarSync Flex V3 is the third and current generation hardware that uses an updated control processor to achieve higher synchronous rates of up to 3.072Mbps. Flex V3 is designed to be fully industrial temperature rated (-40oC to +85oC). Flex V3 uses a slightly updated driver for Windows and Linux that is fully compatible with earlier products.

My FarSync Flex LED does not light, why?

If using the supplied FarSite USBF cable make sure that the thumb screws that lock the cable to the Flex are fully screwed in.

What does the LED on the FarSync Flex indicate?

The LED on FarSync Flex indicates when power is supplied to the device and that a transmit clock is present (fast flash - 4/s) or that the device is in identify mode (slow flash - 1/s).

My FarSync Flex is not enumerated by the OS?

Is the FarSync Flex Connected via an external hub? If so, is the external hub self-powered (connected to an external power supply) or bus-powered (no external power supply). FarSync Flex is designed to be attached directly to a host PC USB port or via a self-powered external hub, it cannot be used with a bus-powered hub.

Why does my FarSync Flex not run as fast as expected?

Is the FarSync Flex connected to a USB 1.1 (12Mbps) or USB 2.0 (480Mbps) port? On some PC's a pair of USB ports may be rated USB 1.1 and intended for Keyboard and Mouse use only. If the FarSync Flex is connected to a USB 1.1 port, FarSite does not recommend operation at speeds in excess of 1Mbps.

If the FarSync Flex is connected to an external hub and there are other devices attached to the same hub optimal performance may not be achieved. Identify a USB 2.0 port on the host PC and connect the FarSync Flex to that port for best performance.

If your FarSync Flex is configured for NRZI, FM0 or FM1 encoded data, then the maximum data rate to 1563kbps on Flex (V1) - there is no such limit for Flex V2 or V3.

Why does FarSync Flex appear to error?

It may be that the USB port to which the Flex is attached is sharing an IRQ with a driver that is badly behaved. Check with the System Information application. Poor performance may be seen where the relevant USB IRQ is shared with a Display Adapter IRQ.

Try attaching the FarSync Flex to a different USB port.

Why does FarSync Flex appear to disconnect?

If the Flex is connected to a front-mounted USB connector, try connecting the device to a rear-mounted USB connector (fitted directly to the motherboard).

If a spare A-B type High Speed USB 2.0 cable is available, try swapping with the supplied one to see if this resolves the problem.

As another option, open Device Manager and locate the USB Root Hub devices. Right-click Properties and go to the Power Management tab; if "Allow the computer to turn off this device to save power" is checked, try un-checking to see if this resolves the problem.

Why does Windows display "USB Device Unrecognised" when I attach my FarSync Flex?

Unplug, wait for 30 seconds, then re-plug the device to see if this resolves the problem.

Restarting the host PC will usually resolve this problem when unplugging and re-plugging the device does not work.

If the problem persists, contact FarSite for further advice.

Why does Windows display "This Device can perform faster" when I attach my FarSync Flex?

This implies that the FarSync Flex has been attached to a USB 1.1 port. Attach the Flex to a USB 2.0 port for best performance.

When I shutdown my PC, the FarSync Flex remains Powered Up, Why?

This is normally only seen on desktop computers and is unusual on laptop machines. To allow for features such as wake on keyboard or mouse, USB ports are often powered from the +5V standby supply which remains active all the time the PC is attached to the A.C. outlet.

In the case of a desktop machine, some motherboards have a hardware jumper to select +5V main or +5V standby to power the USB ports; in this case selecting +5V main will allow the FarSync Flex to be powered down when the computer is shut down. Other desktop machines may have a BIOS setting to determine what happens to the USB ports when the machine is shut down.

Flex operation problem not answered by the other FAQs, things to try

Make sure the Flex is attached to the PC with the high-quality USB cable supplied by FarSite. If the supplied cable has been lost or damaged, make sure a replacement is USB 2.0 rated with 20AWG for power and 28AWG for signals. USB extension cables may work in some situations, but they cannot be guaranteed to work in all instances. FarSite does not recommend the use of USB extension cables with FarSync Flex.

Try applying the latest service pack(s) and/or other updates applicable to the host PC.

Check if there is a driver or card firmware update in the support section of the FarSite website that addresses the problem – Download_Software.htm.

What Internal Clock Rates does my FarSync Flex Support?

FarSync Flex supports the following Clock Rates using firmware version 2.1 or above:

FarSync Flex Clock Rates (Synchronous, NRZ)

      15,      25,      30,      50,      60,     75,      100,     120,
     125,     150,     200,     240,     300,    375,      400,     480,
     500,     600,     750,     800,     960,    1000,    1200,    1500,
    1600,    1920,    2000,    2400,    3000,    3200,    3840,    4000,
    4800,    6000,    6400,    7200,    7680,    8000,    9600,   12000,
   12800,   14400,   15360,   16000,   16800,   19200,   21600,   24000,
   25600,   26400,   28800,   30720,   31200,   32000,   33000,   33333,
   33600,   36000,
   38400,   40000,   40800,   43200,   48000,   51200,
   56000,   61440,   64000,   76800,   80000,   96000,  102400,  112000,
   22880,  128000,  153600,  160000,  192000,  200000,  204800,  224000,
  245760,  250000,  256000,  307200,  320000,  384000,  409600,  448000,
  491520,  512000,  576000,  614400,  640000,  704000,  768000,  819200,
  832000,  896000,  960000,  983040, 1000000, 1024000, 1088000, 1152000,
 1216000, 1228800, 1280000, 1344000, 1408000, 1472000, 1536000, 1600000,
 1638400, 1664000, 1728000, 1792000, 1856000, 1920000, 1984000, 2000000,
 2048000, 2112000, 2176000, 2240000, 2304000, 2368000, 2432000, 2496000,
 2560000, 2624000, 2688000, 2752000, 2816000, 2880000, 2944000, 3000000,
 3008000, 3072000.

Rates shown in RED are available on Flex (V1) only.
Rates shown in BLUE are available on Flex V2/3 only.
Maximum NRZ rate for Flex (V1)/V2 is 2048kbps. Maximum NRZ rate for Flex V3 is 3072kbps.

FarSync Flex Clock Rates (Synchronous, FM0, FM1, NRZI, Manchester, Differential Manchester)

      15,      25,      30,      50,      60,      75,     100,     120,
     125,     150,     200,     240,     300,     375,     400,     480,
     500,     600,     750,     800,     960,    1000,    1200,    1500,
    1600,    1920,    2000,    2400,    3000,    3200,    3840,    4000,
    4800,    6000,    6400,    7200,    7680,    8000,    9600,   12000,
   12800,   14400,   15360,   16000,   16800,   19200,   21600,   24000,
   25600,   26400,   28800,   30720,   31200,   32000,   33000,   33333,
   33600,   36000,   38400,   40000,   40800,   43200,   48000,   51200,
   56000,   61440,   64000,   76800,   80000,   96000,  102400,  112000,
  122880,  128000,  153600,  160000,  192000,  200000,  204800,  224000,
  245760,  250000,  256000,  307200,  320000,  384000,  409600,  448000,
  491520,  512000,  576000,  614400,  640000,  704000,  768000,  819200,
  832000,  896000,  960000,  983040, 1000000, 1024000, 1088000, 1152000,
 1216000, 1228800, 1280000, 1344000, 1408000, 1472000,
 1536000, 1600000,
 1638400, 1664000, 1728000, 1792000, 1856000, 1920000, 1984000, 2000000,
 2048000, 2112000, 2176000, 2240000, 2304000, 2368000, 2432000, 2496000,
 2560000, 2624000, 2688000, 2752000, 2816000, 2880000, 2944000, 3000000,
 3008000, 3072000.

Rates shown in RED are available on Flex (V1) only.
Rates shown in BLUE are available on Flex V2 and V3 only.
Maximum Coded rate for Flex (V1) is 1536kbps.
Maximum Coded rate for Flex V2 is 2048kbps.
Maximum Coded rate for Flex V3 is 3072kbps.
Flex (V1) only supports FM0, FM1 & NRZI.
Higher clock rates are supported on the Flex V2 and V3 but just for bursts, not with sustained data rates.
The FarSync BERT HS product uses a different version of the FarSync Flex hardware that supports clock
rates up to 16000000, contact us for further details.


FarSync Flex Clock Rates (Asynchronous)

      15,      25,      30,      50,      60,      75,     100,     120,
     125,     150,     200,     240,     300,     375,     400,     480,
     500,     600,     750,     800,     960,    1000,    1200,    1231,
    1500,    1600,    1920,    2000,    2400,    3000,    3200,    3840,
    4000,    4800,    6000,    6400,    7680,    8000,    9600,   12000,
   12800,   15360,   16000,   19200,   24000,   25600,   30720,   32000,
   38400,   48000,   51200,   57600,   61440,   64000,   76800,   96000,
  102400,  115200.

NOTE: 57600 asynchronous clock accuracy is -1.23% and 115200 is +2.56%.

Why do I need to reinstall drivers when I replace one FarSync Flex with another?

Every FarSync Flex has a unique serial number that Windows uses to identify a particular instance of the device. This allows devices to be swapped between USB ports on the same PC without any need to reinstall drivers etc.

This default device-centric behaviour may be changed to be port-centric, so that any FarSync Flex may be plugged into the same USB port on a PC without the need to install drivers etc.

To change the behaviour,

  1. Uninstall all FarSync Flex drivers/applications,
  2. Edit the registry,
  3. Reinstall FarSync Flex devices/applications.

FarSite's fsclean utility is particularly useful for uninstalling all FarSync Flexes, including hidden (no longer attached) devices.

Step 2 requires you to use regedit to add a REG_BINARY value in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags called IgnoreHWSerNum1AFD0721 with a value of 01.

After that change, each Flex plugged into a specific USB port will be seen by host software as being the same device instance. However, if you move a Flex from one port to another then it will be seen as a different instance of the device.

How Can I Show Hidden FarSync Flexes in Device Manager?

By default Device Manager does not show hidden (no longer attached) FarSync Flexes. Device Manager can be made to show hidden devices by adding an environment variable DEVMGR_SHOW_NONPRESENT_DEVICES and assigning it a value of 1.

To add an environment variable right-click (My) Computer | Properties and select Advanced | Environment Variables (ensure that it is added as a system variable).

When Device Manager is restarted, and View | Show Hidden Devices is selected, any hidden devices will be shown. And, for instance, unattached Flex devices can then be uninstalled if required.

How much power does FarSync Flex draw from the USB port?

The FarSync Flex draws around 100mA prior to device configuration. During the USB enumeration phase, FarSync Flex declares that it requires up to 400mA when fully operational. Actual current drawn will be dependent upon port configuration (interface type, clock rate, termination, etc.).

Why does FarSync Flex or another USB device not operate correctly when both devices are attached to my system?

Each individual USB port on a PC will normally deliver up to 500mA to an attached device. For some PC's this does not appear to be the case, especially when other USB ports have power consuming devices attached.

If a USB port cannot deliver adequate power, the FarSync Flex or other device may not function correctly. If this kind of problem is suspected, try removing other bus-powered devices (excluding keyboard/mouse) and reboot the host PC. If this resolves the problem try attaching the other bus-powered devices to different USB ports.

If the host PC cannot provide adequate power for multiple bus-powered devices, try adding an external self-powered USB 2.0 hub (make sure the external power supply is rated at least number of ports x 500mA + 500mA @ 5V).

Last Update: 28 Feb 2020