Applies To:
  • CitectSCADA 3.00

The following are additional information to "Using Allen-Bradley Interchange software with 1784-KT card". The ABKT Interchange now also supports SLC-500. 

Hardware requirements
1784-KT card and network connection to PLC
Setup the board address switches and interrupt jumper on the card.

Software requirements
Install the Allen-Bradley supplied Interchange software 5850-WKTS. Edit AB's CFG_KT.INI file. Run ABICRUN.BAT before entering windows. ABICRUN.BAT would not work if it is started from winstart.bat.

Boards form
Board name: User supplied unique name
Board type: ABKT
Address: 0
I/O Port: not used
Interrupt: not used
Special Opt: not used
Ports form
Port name: User supplied unique name
Port number: not used
Board name: Use the "Board name" from the Boards form
Baud rate: not used
Data bits: not used
Stop bits: not used
Parity: not used
Special Opt: For best performance configure a virtual port for each PLC. Up to 40 ports can be defined. Maxpending * number of ports must not be more than 40.
I/O Devices form
Name: User supplied unique name
Number: Network wide I/O device number

PORT_ID is the communication channel that the Network Interface will use to access a remote PLC station. (e.g. nKT for KT module n (n = 1 to 8));
STATION_NUM is the DH or DH+ node number of the remote PLC station. It must be specified in octal notation and must be between 1 and 376 (octal) inclusive (for Data Highway channels) or 0 and 77 (octal) inclusive (for Data Highway Plus channel)

Protocol: ABKT250 for PLC-5/250
ABKT5 for PLC-5
ABKT3 for PLC-3
ABKT2 for PLC-2
ABKT500 for SLC 500
Port name: Use the "Port name" from the Ports form

RS-232 DF1 and 1747-PIC serial communication support

See Allen Bradley Interchange Software for Windows pages 2-5 to 4-4. For example if the SLC-500 DF1 port is configured as full duplex, 19200 baud, no parity and crc error checking, address 2. If the COM1 port is connected to the SLC 500 DF1 port. The following files must be edited:

system.ini [386enh] section
;Device=v485.386 1747-PIC
;COM1V485 1747-PIC driver
;COMxIRQy x is the com port 1 to 4 and y is the interrupt 3,4,5,7,10,11,12 or 15.


In the IO Device Form the SLC 500 address will be 8kt,2


See Allen-Bradley Interchange Software Release 6.0.3, Reference Manual, pages 1-30 to 1-38 and pages 2-49 to 2-54.

Unsolicited Messages

If the Address of an IO device in is blank then this device is for processing unsolicited messages from all PLCs. The protocol must be ABKT2 since only PLC-2 type messages are supported. Only one device should be used in this way to process unsolicited messages.

Citect.ini option

UnsolicitedBytes = 1024

The default size of the PLC-2 data table is 512 words (10 to 777 octal). Words 0 to 7 are not accessible.

Standard citect.ini options

MaxPending = 2 (set to 1 if using more than 20 ports)
Block = 192 bytes
Retry = 1
Delay = 0
TimeOut = 4000 milliseconds
PollTime = 60 milliseconds
WatchTime = 30 seconds


  • ABKT.DLL KT Driver for windows using AB Interchange Software
  • AB_2.DBF PLC-2 Variable Template
  • AB_3.DBF PLC-3 Variable Template
  • AB_5.DBF PLC-5 Variable Template
  • AB_5_250.DBF PLC-5/250 Variable Template
  • SLC500.DBF SLC 500 Variable template
  • \WINDOWS\SYSTEM\DTLKTW.DLL Allen-Bradley supplied driver \WINDOWS\SYSTEM\DTLKTWD.EXE Allen-Bradley supplied driver
  • \WINDOWS\SYSTEM\VDF1.386 Allen-Bradley supplied driver
  • \WINDOWS\SYSTEM\V485.386 Allen-Bradley supplied driver

SLC-500 Variables

O:O/b Output image
I:O/b Input image
S:w/b Status words 0 to n
Tf:w.t Timer
Tf:w/b Timer
Cf:w.c Counter
Cf:w/b Counter
Rf:w.r Control
Rf:w/b Control
Bf:w/b Binary
Bf/b* Binary
Nf:w/b Integer
Ff:w/b Floating Point
O:O Output image
I:O Input image
S:w Status words 0 to 96
Tf:w.T Timer
Cf:w.T Counter
Rf:w.C Control
Bf:w Binary
Nf:w Integer
STf:w String type is support for SLC-500 in Allen-Bradley Interchange Software Release 6.0.3
Ff:w Floating Point


f   File Number 0 to 255 decimal
:w   Element number 0 to 255 decimal
:O I/O   Slot number 0 to 30 decimal
/b   Bit Number 0 to 15 decimal
/b*   Bit Number 0 to 4095 decimal
.T   Timer/Counter Sub Element
PRE   Preset Value
ACC   Accumulated Value
.t   Timer bits
EN   Enable
TT   Timing
DN   Done
.C   Control Sub Element
LEN   Length
POS   Position
.c   Counter bits
CU   Count Up
CD   Count Down
DN   Done
OV   Overflow
UN   Underflow
.r   Control bits
EN   Enable
EU   Enable Unloading
DN   Done
EM   Empty
ER   Error
UL   Unload
IN   Inhibit Comparisons
FD   Found


37 Inconsistent Maxpending specified. You may get this error if you are using the driver with version 2.0 CITECT. The maxpending in [ABKT?] and [ABKT] in citect.ini (alternate citect.ini is not supported) must be the same.