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The following table lists the complete (Modem Control) pin functions of the
KITZ and the PC:
Pin KITZ (DTE) PC AT LAPTOP PC or PS/2 Type
No Connector 9 Pin female connector 25 Pin male connector
(DTE) (DTE)
1 Protective Ground Carrier Detect (CD) Protective Ground
2 Transmit Data (Tx) Receive Data (Rx) Transmit Data (Tx)
3 Receive Data (Rx) Transmit Data (Tx) Receive Data (Rx)
4 Request To Send Data Terminal Ready Request To Send
(RTS) (DTR) (RTS)
5 Clear To Send (CTS) Signal Common Clear To Send (CTS)
6 Data Set Ready (DSR) Data Set Ready (DSR) Data Set Ready (DSR)
7 Signal Common Request To Send (RTS) Signal Common
8 Carrier Detect (CD) Clear To Send (CTS) Carrier Detect (CD)
9 Ring Indicator (RI)
20 Data Terminal Ready Data Terminal Ready
(DTR) (DTR)
22 Ring Indicator (RI)
Table 2 KITZ and PC RS232 port modem control connections.
4.2 K-Bus connection
4.2.1 Recommended cable
Twisted pair of wires with outer screen, to DEF STANDARD 16-2-2c 16 Strands
of 0.2mm diameter, 40mý per metre per core, 171pF per metre (core to core),
288pF per metre (core to screen).
4.2.2 Connection method
K-Bus is a multi-drop standard. The K-Bus cable extends from a KITZ interface unit
and is daisy-chained from one slave device to the next in a radial fashion. The
total K-Bus cable from the master control unit to the farthest slave device is known
as a spur. No branches may be made from the spur.
4.2.3 Cable termination
Four millimetre looped screw termination or fast-on connection (as per MIDOS
standard terminations). The outer screen should be earthed at one point of the
cable only, preferably at the connection to the KITZ unit. The transmission wires
should be terminated using a 150ý resistor at both extreme ends of the cable.
4.2.4 Cable polarity
Polarisation is not necessary for the 2 twisted wires.
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