GE DGP Series, Instruction Manual

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GE Power Management DGP Digital Generator Protection System 9-
15
9 COMMUNICATIONS 9.5 MODBUS MEMORY MAPPING
9
9.5.8 OSCILLOGRAPHY REPORT MEMORY MAP
Range: 1400 to 16FBH
The oscillography report contains three parts: the oscillography header, active settings for the particular fault,
and oscillography data. Since the memory map is not sufficient for the entire oscillography report, the map is
designed such a way that the fault number and cycle number for the oscillography in interest are selected and
read from a fixed set of registers. The oscillography header and settings are unique for each fault number and
do not depend on the cycle number. The oscillography data depends both on cycle number and fault number.
All oscillography registers have an address with most significant 6 bits set to 000101B.
a) CONTROL REGISTERS
Range: 17FE to 17FFH
The control registers are written using Modbus Function Code 06/10. These registers are read-write registers
and can be read using Function Codes 03 and 04.
The fault number range is limited by Setting 111: NUM FLTS. The cycle number range is also limited by the
same setting. That is, for one fault the range is 1 to 120, for two faults the range is 1 to 60, and for three faults
it is 1 to 40. In addition, if the fault number is set higher than the number of faults recorded, the DGP slave
responds with ILLEGAL DATA VALUE exception. The number of faults recorded can be obtained by reading
the register 1400H.
Fault Number 1 corresponds to the newest fault and Fault number 3 corresponds to the oldest fault.
You must write the fault number to register 17FFh and the cycle number to register 17FEh
before reading the oscillography data corresponding to this fault.
b) OSCILLOGRAPHY HEADER
Range: 0C00H to 129DH
The first register (0C000H) contains the number of faults recorded. The rest of the registers contain the pre-
fault values, fault values, and the sequence of events. In essence, this block is identical to the fault report
header. All registers are read-only and can be read by Function Codes 03/04.
When a request is made to read these registers, the DGP relay looks at register 17FFH. If it is with in range
then it responds with the oscillography header corresponding to the fault number in the register 17FFH. If the
number is not valid, the DGP slave responds with ILLEGAL DATA VALUE exception.
c) OSCILLOGRAPHY SETTINGS
Range: 1400 to 1483H
Oscillography settings start from register 1400H. All registers are read-only and can be read using function
codes 03H/04H.
When a request is made to read these registers, the DGP relay looks at register 17FFH. If it is with in the range
then it responds with the oscillography settings corresponding to the fault number put in the register 17FFH. If
the number is not valid the DGP slave responds with ILLEGAL DATA VALUE exception.
NOTE