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TPCMQ48 SERIES
INSTALLATION & OPERATING MANUAL
Manual No. tpcmq48-4
tpcmq48-man-rev4-0116.indd
20.2.4
BUS speed
The I²C interface as used in TPCMQ48 is designed to run with a serial clock speed 100kHz.
20.3
Operation and Functions
20.3.1 Digital Functions
Digital status functions are provided by a PCF8574 8-bit I/O port device. When this device
is read by the I²C bus controller a single 8-bit word provides the information given in the
following table.
BIT FUNCTION
GOOD
STATE
MEANING
0
Input Power Fail
0
A “1” provides warning of input supply failure.
1
Output Power Good
0
Output voltage is within specified limits.
2
Temperature Warning
0
Temperature exceeds normal operating limit.
3
Fan #1 Good
1
Fan running at >80% nominal speed.
4
Fan #2 Good
1
Fan running at >80% nominal speed.
5
Fan #3 Good
1
Fan running at >80% nominal speed.
6
-
1
Not used
7
Temperature Alarm
1
Ambient temperature exceeds 70°C, unit switched
off. Also indicates OVP and Inhibit activated.
PCF8574 slave address
BIT
7
6
5
4
3
2
1
0
HEX ADDRESS
RANGE
0x40 – 0x4E
VALUE
0
1
0
0
GA2 GA1 GA0 R/W
Note that if a zero is written to bit 7 in a data byte, the unit will be inhibited. The default
state is enabled.
20.3.3 Analogue Functions
Analogue status functions are provided by two PCF8591 4-channel 8-bit A/D converter
devices. When these devices are read by the I²C bus controller a single 8-bit word provides
the information given in the following table.
Device U1
A/D FUNCTION
A/D FUNCTION
1
Output voltage
3
Not used
2
Output current
4
Not used
PCF8591 slave address – device U1
