Technical Guide
P92x/EN CT/E11
Modbus Protocol
MiCOM P921-P922-P923
Page 7/118
1.1.5
Address of the MiCOM relays
The address of the MiCOM relay on a same MODBUS network is situated between 1
and 255. The address 0 is reserved for the broadcast messages.
1.2
MODBUS functions of the MiCOM relays
The MODBUS functions implemented on the MiCOM relays are :
Function 1 or 2 : Reading of n bits
Function 3 or 4 : Reading of n words
Function 5 : Writing of 1 bit
Function 6 : Writing of 1 word
Function 7 : Fast reading of 8 bits
Function 8 : Reading of the diagnosis counters
Function 11 : Reading of the Event counter
Function 15: Writing of n bits
Function 16 : Writing of n words
1.3
Presentation of the MODBUS protocol
MODBUS is a master-slave protocol whereby every exchange involves a master query
and a slave response.
1.3.1
Frame size received by the MiCOM P92x relay
Frame transmitted by the master (query) :
Slave number
Function code
Information
CRC16
1 byte
1 byte
n bytes
2 bytes
Slave number :
The slave number is situated between 1 and 255.
Function code :
Requested MODBUS function (1 to 16).
Information :
Contains the parameters of the selected function.
CRC16 :
Value of the CRC16 calculated by the master.
NOTA :
the MiCOM relay does not respond to globally broadcast frames
sent out by the master.
Summary of Contents for MiCOM P921
Page 1: ...MiCOM P921 P922 P923 Voltage and Frequency Relays Technical guide P92x EN T E11...
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Page 4: ...P92x EN T00 E11 Technical Guide Content Page 2 2 MiCOM P921 P922 P923 BLANK PAGE...
Page 5: ...Technical Guide Px2xx EN SS A11 SAFETY SECTION SAFETY SECTION...
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Page 8: ...Px2xx EN SS A11 Technical Guide SAFETY SECTION Page 2 6 BLANK PAGE...
Page 12: ...Px2xx EN SS A11 Technical Guide SAFETY SECTION Page 6 6 BLANK PAGE...
Page 13: ...Technical Guide P92x EN GS E11 MiCOM P921 P922 P923 aBCD Getting Started...
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Page 33: ...Technical Guide P92x EN CO E11 MiCOM P921 P922 P923 aBCD Connection Diagrams...
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Page 45: ...Technical Guide P92x EN TD E11 MiCOM P921 P922 P923 Technical Data...
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Page 76: ...P92x EN TD E11 Technical Guide Technical Data Page 30 30 MiCOM P921 P922 P923 BLANK PAGE...
Page 77: ...Technical Guide P92x EN FT E11 MiCOM P921 P922 P923 User Guide...
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Page 258: ...P92x EN CT E11 Technical Guide Courier Database Page 68 118 MiCOM P921 P922 P923 BLANK PAGE...
Page 296: ...P92x EN CT E11 Technical Guide Courier Database Page 106 118 MiCOM P921 P922 P923 BLANK PAGE...
Page 298: ...P92x EN CT E11 Technical Guide IEC 60870 5 103 Page 108 118 MiCOM P921 P922 P923 BLANK PAGE...
Page 308: ...P92x EN CT E11 Technical Guide IEC 60870 5 103 Page 118 118 MiCOM P921 P922 P923 BLANK PAGE...
Page 309: ...Technical Guide P92x EN IN E11 MiCOM P921 P922 P923 abcd Installation...
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Page 312: ...P92x EN IN E11 Technical Guide Installation Page 2 10 MiCOM P921 P922 P923 abcd BLANK PAGE...
Page 319: ...P92x EN IN E11 Technical Guide Installation Page 10 10 MiCOM P921 P922 P923 abcd BLANK PAGE...
Page 320: ...Technical Guide P92x EN CM E11 MiCOM P921 P922 P923 abcd Commissioning Guide...
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Page 351: ...Technical Guide P92x EN RS E11 MiCOM P921 P922 P923 Test Report...
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