Safety
information
Product
information
Mechanical
installation
Electrical
installation
Getting
started
User Menu A Commissioning
Advanced
Parameters
Diagnostics Optimization CT MODBUS RTU Technical Data
E300 Design Guide 235
Issue Number: 1
Wire-break detection
It may be important to detect a break in the connections between the drive and the position feedback device. This feature is provided for most position
feedback devices either directly or indirectly as listed below.
Position feedback power supply trips
The position feedback power supply from the drive can be switched off by the drive either because the power supply is overloaded (Encoder 1 trip) or
because the internal 24 V supply within the drive is overloaded (PSU 24 V trip). The internal 24 V supply provides power for the position feedback
power supply, user 24 V output, digital I/O, option modules etc. To ensure that an Encoder 1 trip is not initiated when the internal 24 V is overloaded,
and subsequently switched off by the drive, there is a delay of 40 ms in the detection of Encoder 1 trip. It is possible for other position feedback trips,
such as wire break detection (i.e. Encoder 2), to occur when the power supply is removed from the position feedback device. Therefore overloading
the internal 24 V supply or the position feedback supply could result in an immediate Encoder 2 trip. To ensure that the correct reason for the trip is
given PSU 24V and Encoder 1 trips override an existing Encoder 2 to Encoder 6 trip. This means that both the original trip (Encoder 2 to Encoder 6)
and then the new trip (PSU 24 V or Encoder 1) are stored in the trip log.
Drive Encoder Error Detected (C22) is set if an error has been detected with the position feedback device connected to the Drive position feedback
interface. This parameter is useful if encoder trips have been disabled by setting bit 3 of Drive Encoder Error Detection Level (C21). It should be noted
that this bit is not set if specific trips are disabled with bits 0 to 2 of Drive Encoder Error Detection Level (C21).
The speed feedback from the Drive position feedback interface can be used as a source to control a parameter. The speed feedback is scaled to give
a value as a percentage of Drive Encoder Source Maximum Reference (C23) in 0.1 % units. Normally the destination is updated every 4 ms.
Drive Encoder Type (C01): EnDat
Drive Encoder Calculation Time (C24) is the time from the first edge of the clock signal from the position feedback interface until the encoder has
calculated the position and is ready to return this information. This is used to calculate the overall time for a message interchange with the encoder.
Device Detection method Trip produced
AB, FD, FR, AB Servo,
FD Servo, FR Servo
Hardware detectors on the A1, B1 and Z1 signal detect a wire break. Encoder 2
SC, SC Servo,
SC Hiperface, SC EnDat,
SC SSI, SC SC
The magnitudes of the sine wave signals are monitored and if Sine
2
+Cosine
2
is less than
the value produced by two valid waveforms with a differential peak to peak magnitude of
0.25 V (
1
/
4
of the nominal level) then a trip is initiated. This detects wire break in the sine and
cosine connections.
Encoder 2
SC Hiperface, SC EnDat,
EnDat, BiSS
Wire break in the comms link is detected by a CRC or timeout error. Encoder 4, Encoder 5
SSI, SC SSI
Wire break detection in the comms is difficult with these devices. However, if power supply
alarm bit monitoring is enabled the drive will be looking for a one at the start of the message
and a zero to indicate that the power supply is okay. If the clock stops or the data line is
disconnected the data input to the drive may stay in one state or the other and cause a trip.
Encoder 5, Encoder 6
C22 Drive Encoder Error Detected
Mode RFC-A, RFC-S
Minimum 0 Maximum 1
Default Units
Type 1 Bit Volatile Update Rate Background write
Display Format Standard Decimal Places 0
Coding RO, ND, NC, PT
C23 Drive Encoder Source Maximum Reference
Mode RFC-A, RFC-S
Minimum 0 Maximum 33000
Default 1500 Units
Type 16 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 0
Coding RW, BU
C24 Drive Encoder Calculation Time
Mode RFC-A, RFC-S
Minimum 0 Maximum 20
Default 5 Units μs
Type 8 Bit User Save Update Rate Background read, auto-configuration write
Display Format Standard Decimal Places 0
Coding RW
To Next Page
Loading...
