ABB CS31 distributed debugging

2.4 Other special units

07 GV 93: Three axis positioning module, receiving incremental encoder feedback (± 10V set value), with a maximum speed of 100m/min, supporting 300 positioning datasets/axes.

UCZA/UCZB: Early high-capacity central unit (8k/16k instructions), supporting SCZ bus expansion couplers.

PCZB/CS20:2k instruction compact unit with built-in high-speed counter.

CS31 System Bus (RS485) Installation Specification

The system bus is the core of the CS31 distributed architecture, and incorrect wiring can lead to unstable or complete communication interruption.

3.1 Bus cable specifications

Shielded twisted pair cables must be used, recommended models: ALCATEL MCX-T or DRAKKA dracoda 2903. Specific requirements:

Cross sectional area: 0.22~0.8 mm ² (AWG 24~18)

Stranded density:>10 twists/meter

Characteristic impedance: 100~150 Ω

Distributed capacitance:<150 nF/km

DC resistance: ≤ 100 Ω/km

3.2 Bus topology and terminal resistance

The CS31 bus adopts a master-slave architecture, with only one master station on a bus. The maximum number of stations is 31 slave stations+1 master station, and the maximum length between the two ends of the bus is 500 meters.

120 Ω, 1/4W terminal resistors must be installed at both ends of the bus (connected between BUS1 and BUS2 terminals). The following central units have built-in resistors: UCZA/UCZB, 07 CS 61, 35 CS 91, which must be connected at the end of the bus. For the 07 KR/KT series central unit, if it is located at the bus endpoint, an external 120 Ω resistor needs to be connected between terminals 1 (BUS2) and 2 (BUS1) of the ECZ base.

3.3 Shielding Grounding

The shielding layer should be continuously looped through the SHIELD terminals of all CS31 devices and only grounded directly near the main station. If there are strong noise sources (such as frequency converters, motors, etc.) inside the control cabinet, it is recommended to ground the shielding layer through a 1nF Y-class capacitor to avoid low-frequency ground loop currents.

Important rules:

All CS31 products installed in the same control cabinet must be connected to the same ground.

The grounding wire should be as short as possible (less than 25cm).

Connect cables with a cross-sectional area of at least 16mm ² between different control cabinets.

Noise components (frequency converters, motors) should not share grounding between two cabinets, and their grounding points should be close to the noise source itself.

3.4 Power grounding type

Select the appropriate grounding method based on the on-site power supply system:

IT system: The neutral point is not grounded, and the metal casing is grounded. In noisy environments, each control cabinet should use a shielded isolation transformer (even the 24V DC version requires it).

TT system: neutral point grounding, metal shell grounding. This is a conventional industrial power distribution method.

Address setting and I/O address mapping

4.1 DIP switch on ECZ base

All remote I/O units are installed on the ECZ plug-in base. The DIP switch on the base is used to set the unit address (group number):

Switch number function

Set the address from 2 to 7 (binary weighted: 32/16/8/4/2/1), ON=1

For the configurable I/O unit (ICS 08 L1): ON=all channels are forced to output, OFF=configured by the program

8 channel number offset: OFF=channel 00~07, ON=channel 08~15

Example of address calculation: Set DIP switches 2 (32), 3 (16), and 5 (4) to ON, then address=32+16+4=52.

4.2 I/O Address Structure in Central Unit

In the user program, the address format for remote I/O points is E xx, yy (input) or A xx, yy (output), where:

Xx: Unit address (group number, set by DIP switches 2-7)

YY: Channel number within the unit (00~15, affected by DIP switch 8)

For 07 KR 91/07 KT 92/07 KT 93 as the main station:

It is recommended to use even addresses (8,10,12... 60) for binary units

The simulation unit only allows the use of addresses 0-5

Switch 8 is recommended to be set to OFF (channels 00~07)

Note: If two remote units are set to the same address, the master station will consider them disconnected and report an FK3 type error (error identifier 15) when detecting signal conflicts.

Bus refresh time calculation

The master CPU polls all slave stations at a fixed cycle. The bus refresh time (T rb) depends on the number and type of slave stations. The calculation formula is:

For the 90 series main station (07 KR 91, etc.): T rb=T offset+T communication

For the 30 series main station (07 KR 31, etc.): T rb=T offset+T communication+n × 100 µ s

among which

T offset=2000 µ s (fixed)

N=Number of slave stations

T communication refers to the communication time of various types of slave stations, with typical values as follows:

Unit type communication time

07 KR/KT 31/91/92/93 (slave, default configuration) 750 µ s

ICSI 08 D1 (8 inputs) 323 µ s

ICSO 08 R1 (8 relay outputs) 260 µ s

ICSK 20 F1 (12 inputs/8 relay outputs) 452 µ s

ICSE 08 B5 (8 analog inputs, 12 bits) 1355 µ s

ICSA 04 B5 (4 analog outputs) 700 µ s

Calculation example: A 90 series master station with 1 ICSK 20 F1 (452 µ s)+1 ICSO 08 R1 (260 µ s)+1 ICSI 16 E1 (387 µ s)+1 ICFC 16 L1 (516 µ s)+1 ICSC 08 L1 (387 µ s). The sum of T communication is 2002 µ s, plus a T offset of 2000 µ s, resulting in T rb ≈ 4ms.