Description; Communications Settings; Supported Modbus Functions; B.1.1 Description - GE ALPS Instruction Manual

APPENDIX B
APPENDIX B MODBUSB.1 MODBUS INTRODUCTION
This appendix describes the functional specifications/memory map of the Modbus RTU protocol interface for the ALPS
Advanced Line Protector System revision A (ALPS-A). The specifications cover Modicon Modbus application messages
supported by the ALPS interface software module.
The ALPS relay provides the user interface to configure the Modbus communications parameters. The Modbus device
address and the Baud Rate for RS485/RS232 port are configurable from the MMI of the ALPS.
There will be a delay before the ALPS is ready to answer Modbus requests from the Modbus master on power up. This is
due to internal data and baud rate synchronized tasks to be performed. Device address changes and baud rate changes
will affect the operation of the device once the device is communicating.
Before using the ALPS in a Modbus RTU network, the communications parameters must be set appropriately. The Baud
Rate and the Modbus unit address must be set in the ALPS device. The ALPS does not respond to Modbus address 0.
Table B–1: REQUIRED SETTINGS FOR MODBUS COMMUNICATIONS
SETTING MODBUS VALUE/MEANING
UNIT ID Modbus Address: valid only from 1 to 247.
Modbus Baud Rate: 1200, 2400, 4800, and 9600
REMOTE BAUD RATE
The ALPS will support a subset of Modbus Commands. All these commands are supported are listed below.
FUNCTION NAME
CODE (DEC)
03/04 Read Holding (Setpoint) Registers;
Read Input Registers
05 Force Single Coil
06 Preset Single Register
16 Preset Multiple Registers
Both monitoring and control is possible using read and write functions mentioned above. The following table shows the
device register categories.
REGISTER TYPE CATEGORY
Input Registers Fixed Value Registers
Input Registers Dynamic Value Registers
Input Registers Fault Registers
Report Registers Event Registers
Report Registers Fault Report Registers
Report Registers Oscillography Report Registers.
Setpoint Registers Setting Registers
Coil Registers Coil Command Registers
GE Power Management
PURPOSE
Reading the setpoint/actual value
registers
Activate single coil or control
trigger
Writing one register
Writing one or more registers
START
ADDRESS
0000
1000
1500
2000
20000
20000
3000
500
ALPS Advanced Line Protection System
B.1 MODBUS INTRODUCTION
B.1.2 COMMUNICATIONS SETTINGS
FACTORY DEFAULT VALUE
0000
9600
B.1.3 SUPPORTED MODBUS FUNCTIONS
REGISTER GROUPS
Setpoint registers; control registers;
dynamic values, fixed values, faults,
events, and reports
Coil registers
Setpoint registers; control registers
Setpoint registers (limited set only: Date,
Time, Station ID and Line ID)
CONTENTS
Fixed data reported by the device.
Metering data and dynamic status data.
Summary of fault data.
Summary of Event data.
Report data
Report data.
Device settings.
Command coils used for activation.

B.1.1 DESCRIPTION

B
ACCESS
Read Only
Read Only
Read Only
Read Only
---
Read Only
Read/Write
Write Only
B-1