GE P485 instruction manual Advanced functions, Control and status registers

GE Consumer & Industrial

P485 Modbus to Profibus Converter

Chapter 8: Advanced functions

DESCRIPTION

CONTROL REGISTER (PROFIBUS CONTROL SYSTEM TO P485)

Control and status registers

The control/status registers forms an interface for exchanging information between the fieldbus control system and the P485.

The main purpose of these registers is to report Modbus network related problems to the fieldbus control system. This interface is also used to ensure that only valid data is going out on the sub-network and that valid data is reported back to the fieldbus control system. See 8-4 “Input/output data during startup”.

Using these registers, it is also possible for the fieldbus control system to instruct the P485 to enable / disable specified nodes.

By default, these registers are located in the internal memory buffer at 0x000 - 0x001 (Status Register) and 0x200 - 0x201 (Control Register), however they can be disabled using EnerVista P485/D485 Setup, see Modbus network configuration on page 4–13.Disabling these registers will release the 2 reserved bytes in the internal memory buffer, however, the Status and Control functionality will not be available.

The handshaking procedure described on page 8-3must be followed for all changes to these registers

Bytes 0 and 1 of the control register are shown below.

		Byte 0 (Offset 0x200)								Byte 1 (Offset 0x201)
15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
-	-	-		Control Code							Data

P485 MODBUS TO PROFIBUS CONVERTER – USER GUIDE 8–1