Flowserve DDC-100 Modbus Direct-to-Host - Manual (Page 2)

FCD LMAIM4019-00 DDC-100 Direct-to-Host Programming Guide i
Contents
1 Introduction 1
1.1 Premise 1
1.2 Emphasis 1
1.3 Audience 2
2 Direct-to-Host Valve Control 3
2.1 Advantages of Direct-to-Host Control 3
2.2 Deliverables for Successful Direct-to-Host Implementations 4
3 Field Unit Monitoring and Control 5
3.1 Use of Coils and Registers for Monitoring and Control 5
3.2 Modbus 6
3.2.1 Modbus Function Code 01 (Read Coil Status) 7
3.2.2 Modbus Function Code 02 (Read Input Status) 8
3.2.3 Modbus Function Code 03 (Read Holding Register) 11
3.2.4 Modbus Function Code 04 (Read Input Register) 18
3.2.5 Modbus Function Code 05 (Force Single Coil) 18
3.2.6 Modbus Function Code 06 (Preset Single Register) 19
3.2.7 Modbus Function Code 08 (Diagnostics) 23
3.2.8 Modbus Function Code 15 (Force Multiple Coils) 24
3.2.9 Modbus Function Code 16 (Preset Multiple Registers) 24
4 The DDC-100 Network 27
Belden 3074F Specifications 27
Belden 3105A Specifications 28
Belden 9841 Specifications 28
4.1 Field Unit Network Communication Channels 28
4.1.1 Field Unit Network Bypass Relays 29
4.1.2 Field Unit Repeater Circuits 29
4.2 Network Topologies 29
4.2.1 Redundant Loop 29
4.2.2 Single-Ended Loop 31
4.2.3 Single-Line Multi-drop 32
4.3 Network Polling 33
4.3.1 Network Communication Errors 35
4.3.2 Network Communication Examples 36
4.4 Network Control 38
4.4.1 Ladder Logic Routines 38
4.4.2 Software Control Modules (C++ or Visual Basic Program) 38
4.4.3 Personal Computer with a Graphical User-Interface 39
5 Interfacing Hardware for the DDC-100 Network 41
5.1 RS-232 to RS-485 Converters 41
5.1.1 RS-232/RS-485 Control Line Steered Converter (P/N 61-825-0966-4) 43
5.1.2 RS-232/RS-485 Converter with RS-485 Self-Steering (P/N 61-825-1032-4) 45
5.2 RS-485 Connection Direct to the DDC-100 Field Unit 48
6 Programming Recommendations 49
6.1 Monitoring Field Unit Status 49
6.2 Issuing Control Commands 50
A Typical DDC-100 Network Installation Assignments 53
Project supplier responsibilities 53