Pmbus Command Set; Read Status; Clear Faults; Operation (On/Off) - TDK-Lambda RFE2500 Series Instruction Manual

5.2

PMBus Command Set

The interval between two consecutive commands to the power supply should be at least 25ms to ensure proper
monitoring functionality.
5.2.1

Read Status

This Command is used to read the status of the Power Supply. The Status information is stored in a special register
called the "STATUS REGISTER". The PMBUS reads 8 different types of Faults and Warnings.
Command Used
D0h
Fault is indicated by "1". No fault is indicated by "0".
For Example:
Faults
DC Fail
Over Temperature Protection
Over Temperature Alarm
Fan Fail
AC Fail
Over Voltage Protection
Programmed Voltage
more than allowed
Command Error
(*1) If Max Allowed Voltage is set to 48V and Programmed Voltage is set to 50V, Output will be programmed to 48V, Bit
No 6 will be "1", and SMBALERT will become "LOW".
(*2) If any Command sent is not understood by the Supply, bit no 7 will be "1" and SMBALERT will become "LOW".
5.2.2

Clear Faults

This command is used to clear the "STATUS REGISTER" after any fault occurs.
If the CLEAR_FAULTS command is not sent after any fault, the "STATUS REGISTER" will not be cleared.
SMBALERT signal will remain "LOW" until "CLEAR_FAULTS" command is sent.
If a Fault or Warning is still present after "CLEAR_FAULTS" is sent, "STATUS REGISTER" will be updated and the
SMBALERT signal will be "LOW" again.
Command Code
03h
5.2.3

Operation (ON/OFF)

Command Code
01h
01h
If the Power Supply is turned OFF with the "OPERATION OFF" command, the Supply can be turned ON with the
"OPERATION ON" command only. Enable signal is disabled.
5.2.4

Commands to Read Inventory Details

Command Name
PMBUS_REVISION
MFR_ID
MFR_MODEL
MFR_OUTPUT
MFR_REVISION
MFR_LOCATION
MFR_DATE
MFR_SERIAL
All details except for ‹PMBUS_REVISION› are stored in ASCII format.
If DC Fail occurs, READ_STATUS will return 01h. SMBALERT will go "LOW".
If AC Fail occurs, READ_STATUS will return 11h. SMBALERT will go "LOW".
Bit No in
Type Status
Register
FAULT 0 Output Voltage < 85~95% of Set Vout
FAULT 1 Internal temperature higher than safe limit
WARNING 2 Internal temperature ~ 10℃ below safe limit
FAULT 3 One or both Fans are not working
FAULT 4 Input Voltage <85Vac / >270Vac
FAULT 5 Output Voltage > 1.15xVset
WARNING 6 Programmed Voltage more than Max
Allowed Voltage (*1)
WARNING 7 Command not understood by Power Supply (*2)
Command Code
98h
99h
9Ah
D1h
9Bh
9Ch
9Dh
9Eh
Type
Read Byte
Meaning
Type
Send Byte
Type
R/W Byte
R/W Byte
Type
Read Byte
Read Block
Read Block
Read Block
Read Block
Read Block
Read Block
Read Block
21
#Data bytes
1
Main Output Behavior
Output OFF/Output Low
Output OFF
Output ON
Output OFF
Output OFF/Output ON
Output OFF
Output ON
Output ON
#Data bytes
0
#Data bytes
00h=OFF
80h=ON
#Data Bytes
1
16
16
16
16
16
16
20