TwinCAT System Manager: Reference

Beckhoff C1220/FC200x/CX1500-M200

The C1220 is an active ISA master card for the Beckhoff Lightbus. Up to 254 Lightbus nodes ("Boxes") can be connected into a ring circuit. Individual boxes and sometimes separate I/O data boxes can be updated selectively and on a priority basis (Beckhoff CDL concept).

The DPRAM of the C1220 is 4 kBytes. There are no interrupts used.

The FC2001 and  FC2002 are PCI bus cards which are otherwise no different from the C1220. The FC2002 supports two independent Lightbus rings (works like two independent C1220/FC2001 cards).

The CX1500-M200 is a Beckhoff Lightbus Master interface for the  CX1000 Embedded-PC series.  Again, from the functional standpoint a CX1500-M200 doesn't differ from a C1220 card. 

Context menu

Beckhoff C1220/FC200x 1:

Append Box... <Insert>

Adds Beckhoff Lightbus boxes to the configuration. The order must correspond with the physical order inside the fiber-optic ring! For a list of all currently supported Beckhoff Lightbus devices, see "Lightbus - Overview" page.

Delete Device... <Del>

Removes the C1220 fieldbus card and all subsidiary elements from the I/O configuration.

Online Reset

Initiates an online reset on the fibreoptic ring.

Break Location Test

Initiates a ring break test on the fibreoptic ring. This Lightbus-specific feature brings up the "Box" position, the fiber-optical ring is currently interrupted.

Export Device

Exports all device settings made at this Lightbus device into a file (*.tce), including eventually available mapping information with Diagnosis Inputs,

Import Box

Imports formerly saved node ("Box") configurations, including attached Bus Terminals and available variable links, if wanted.

Scan Boxes

Scans the ring for deployed Lightbus nodes (including attached Bus Terminals).


”C1220”, "FC200x" or "CX1500-M200" Tab

Beckhoff C1220/FC200x 2:


Address:  For offline configuration, enter the appropriate DPRAM card address here. 
: Under TwinCAT 2.9, if the active target system is in "Config Mode",  the online feature  "Scan Devices.." will find the Lightbus interface card(s) and its address(es) automatically!

    For C1220 only: This address is jumped on the card and can be set to the following (jumper settings J1 - J6):

    Hint: At CX1500-M200 interfaces, the appropriate address belongs to the manufacturer settings!


PCI Slot/Ring: (FC2001/FC2002) Gives the logical PCI slot and in addition for FC2002 whether ring A or ring B is here in use, as info.

Search: Searches the computer for C1220 and/or FC2001/FC2002 and sets the address/slot number correspondingly.

Check number of boxes: If you tick this checkbox, when the card is initialised the number of boxes which are physically present is compared with the number entered under this card in the System Manager. If the numbers do not comply an error is triggered.

System Start Despite Optical Fibre Error: A warning is given rather than halting the TwinCAT start process.

K-Bus Update with Broadcast Telegram (0x80): Decides whether K-Bus update should take place individually per Bus Coupler or for all Bus Couplers together via broadcast telegram when Bus Couplers are connected.

Reserved CDL’s: The C1220 has eight priority channels (CDLs) which, under normal circumstances, are also used by the System Manager. If individual CDL’s are unused - in non-standard applications - these must be indicated here.

Firmware: Displays the firmware version of a found Beckhoff Lightbus interface card (for older C1220s ”Found” only).

Bus Utilization (%):  Displays the estimated total utilization of the bus bandwith (the total of all used CDLs). Upon the displayed value, it has to be decided whether balancing the bus load onto another Lightbus ring could be necessary.


”(Online) DPRAM” Tab

See ”Online Display of DPRAM


”CDL” Tab

See ”CDL Configuration” .


Diagnosis Inputs

The C1220 as well as the FC2001, FC2002 and CX1500-M200 show up in the System Manager with below described diagnosis and control outputs for the status of the fiber optical ring and the Lightbus interface card itself. 

Beckhoff C1220/FC200x 3:


Variable Description
DeviceState General status, assumes values 0 (o.k.) and 1 (error) only
DeviceIioFunc Number of function at which error occurred (see C1220 manual also)
DeviceIioFuncArg Function argument (see C1220 manual also)
BoxWithError Number of box at which error has occurred
ErrorCounter General Error Counter (DPRAM offset 0xEE0)

The Lightbus interface card has several error counters implemented for detection of I/O problems. These counters are accessible from DPRAM starting at offset 0xEE0 as  16-bit values. There is no overflow handling or reset of these counters implemented by the C1220/FC200x firmware. The counter, who reflects the errors detected by the internal address check (0xEEA) doesn't increment the ErrorCounter.

ErrCntRec1 Error detected by Receiver 1

Received address and/or control bytes unequal the corresponding sent bytes.
Receiver 1 alternates with Receiver 2 to compensate the execution time spend for the  handling of the interrupt service routines (ISR). ErrCntRec1 and ErrCntRec2 both increment the sum ErrorCounter (see above)

ErrCntRec2 Error detected by Receiver 2

Received address and/or control bytes unequal the corresponding sent bytes.
Receiver 2 alternates with Receiver 1 to compensate the execution time spend for the handling of the interrupt service routines (ISR). ErrCntRec1 and ErrCntRec2 both increment the sum ErrorCounter (see above)

ErrCntTimeout Timeout during telegram receiving
ErrCntParity Telegram received with CRC error
AddressCheckErrCnt Error at internal address check (DPRAM offset 0xEEA).

If this counter increments, an address check and count telegram with logically wrong content has been received (AD <> D3)

AddressCheckModule If inside the C1220/FC200x error mask bit 1 is set, this cell contains the module address of the box which caused the error.

Control Outputs

Via the General Control Block (GCB), the supervision of the finalization of the different process images is handled. The control bits related to the error detection are described below.

Beckhoff C1220/FC200x 4:

Variable Description
GCB-C0 If this bit is set (default), the address check is active. For detection of parity errors, this bit has to be active
GCB-C1 If this bit is set, the address check is even active at LWL errors (problems related to the fiber-optical conductor)