GE P742

P74
x/EN SC/Na7
SCADA Communications
(SC) 13
-14 MiCOM P74
1, P742, P743
SC
2. COURIER INTERFACE
2.1 Courier protocol
K-Bus is based on EIA(RS)485 voltage levels with HDLC FM0 encoded synchronous
signalling and its own frame format. The K-Bus twisted pair connection is unpolarized,
whereas the EIA(RS)485 and EIA(RS)232 interfaces are polarized.
The EIA(RS)232 interface uses the IEC60870-5 FT1.2 frame format.
The relay supports an IEC60870-5 FT1.2 connection on the front-port. This is intended for
temporary local connection and is not suitable for permanent connection. This interface
uses a fixed baud rate, 11-bit frame, and a fixed device address.
The rear interface is used to provide a permanent connection for K-Bus and allows
multi-drop connection. It should be noted that although K-Bus is based on EIA(RS)485
voltage levels it is a synchronous HDLC protocol using FM0 encoding. It is not possible to
use a standard EIA(RS)232 to EIA(RS)485 converter to convert IEC60870-5 FT1.2 frames to
K-Bus. Nor is it possible to connect K-Bus to an EIA(RS)485 computer port. A protocol
converter, such as the KITZ101, should be employed for this purpose.
Alternatively for direct connections, the fibre optic converter card may be used to convert the
rear EIA(RS)485 port into a fibre optic (ST) port.
2.2 Supported command set
The following Courier commands are supported by the relay:
Protocol Layer
Reset Remote Link
Poll Status
Poll Buffer*
Low Level Commands
Send Event*
Accept Event*
Send Block
Store Block Identifier
Store Block Footer
Menu Browsing
Get Column Headings
Get Column Text
Get Column Values
Get Strings
Get Text
Get Value
Get Column Setting Limits
Setting Changes
Enter Setting Mode
Preload Setting
Abort Setting
Execute Setting
Reset Menu Cell
Set Value