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GE
Grid Solutions
DESCRIPTION
CONTROL REGISTER
(DEVICENET CONTROL
SYSTEM TO D485)
D485 MODBUS TO DEVICENET CONVERTER – USER GUIDE
D485 Modbus to DeviceNet
Converter
Chapter 8: Advanced functions
Advanced functions
Control and status registers
The control/status registers forms an interface for exchanging information between the
fieldbus control system and the D485.
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 Input/output data during startup on page 8–4 for details.
Using these registers, it is also possible for the fieldbus control system to instruct the D485
to enable/disable specified nodes.
By default, these registers are located in the internal memory buffer at 0x000 to 0x001
(status register) and 0x200 to 0x201 (control register). However, they can be disabled using
EnerVista P485/D485 Setup – refer to Modbus network configuration on page 4–13 for
details. Disabling these registers will release the two reserved bytes in the internal memory
buffer, however, the status and control functionality will not be available.
The handshaking procedure described on page 8–3 must be followed for all changes to
these registers
Bytes 0 and 1 of the control register are shown below.
Byte 0 (Offset 0x200)
15
14
13
12
11
-
-
-
Control Code
Byte 1 (Offset 0x201)
10
9
8
7
6
5
4
3
2
1
0
Data
8–1
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