The servo valve has one encoder input.
Figure 32: Encoder input
See also document CA63420-001 "User Manual Electrical Interfaces"
The encoder input can be used to measure the position of a hydraulic axis for the position closed loop. The parameter <Type> (0x6202) will select the type of the encoder (SSI binary, SSI gray or incremental) It is possible to map the output of the encoder <EncoderValue> (0x5613) to more than one
<TransducerPort> (0x4032) . In this case the first of this transducer ports is used to initialize the encoder hardware.
Chapter "6.3.9.3 Object 0x6202: Type", page 77
Chapter "6.3.9.6 Object 0x4032: Transducer port", page 78
6.6.1 Object 0x5613: Encoder value
This raw value is the output from the encoder. It can be mapped to a transducer interface to be scaled to the needs of the application.
6.6.2 Object 0x5619: Sensor supply enable
The valve can deliver the power supply for the encoder. It is possible to switch the supply voltage off or to 5 V or to 24 V to match the needs of the encoder hardware.
Value description
s
u Connector SSI / incremental encoder X2
<EncoderValue> (0x5613)
Chapter 6.6.3
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis- tence
Value
range Default
0x5613 0 EncoderValue UINT32 rw N UINT32 None
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis- tence Value range Default 0x5619 0 SensorSupplyEnable UINT8 rw Y 0, 5, 24 0 <SensorSupplyEnable> Description 0 0 V, supply enabled. 5 5 V 24 24 V
6.6.3 Incremental Encoder
The incremental encoder only can measure a relative change in the position and the speed of the axis. To get the absolute position the encoder needs a reference run after power on.
The valve allows an automatically reference run. To start this reference run, switch the
<DeviceMode> (0x6042) to 4 (reference mode) and set bit 9 (axis install mode positive direction) or bit 10 (axis install mode negative direction) of the <ControlWord> (0x6040).
In the first step of the reference run, axis will move with the <ReferencingVelocity> (0x5614) to end of stroke. When the "end of stroke position" is reached, the pressure in the cylinder is rising. So the valve will wait until <PrsActualValue> (0x6381) reaches the <ReferencingForce> (0x561A) to finish the first step.
In the second step of the reference run, the axis is moving slowly back from the "end of stroke position". If <ZPulseTrigger> (0x5617) = 1, the valve is waiting for the Z pulse. If the Z pulse appears or the axis moved the distance <ReferencingStop> (0x561B), the reference run is finished and the <EncoderValue> (0x5613) is set to 0.
A manual search for the reference position is also possible if the <DeviceMode> (0x6042) is switched to 1 or 2 (setpoint input via bus or locally). If the flag <ZPulseEnable> (0x5610) is set, the valve is waiting for the next Z pulse. When the Z pulse appears, the predefined position <ZPulseSet> (0x5612) is copied to the
<EncoderValue> (0x5613) and <ZPulseEnable> (0x5610) is reset to indicate the successful referencing.
Chapter "5.1.2 Object 0x6040: Control word", page 44
Chapter "7.8 Axis position setpoint conditioning / demand value generator", page 192
6.6.3.1 Object 0x5614: Referencing velocity
In the first step of the reference run, the axis will move with this velocity to end of stroke.
6.6.3.2 Object 0x561A: Referencing force
In the first step of the reference run, axis will move to end of stroke. When the "end of stroke position" is reached, the pressure in the cylinder is rising. So the valve will wait until <PrsActualValue> (0x6381) reaches the <ReferencingForce> (0x561A) to finish the first step.
Chapter "7.5.1 Object 0x6381: Actual value", page 169
6.6.3.3 Object 0x561B: Referencing stop
In the second step of the reference run, the axis is moving slowly back from the "end of stroke position". If <ZPulseTrigger> (0x5617) = 1, the valve is waiting for the Z pulse. If the Z pulse appears or the axis has moved the distance <ReferencingStop> (0x561B), the reference run is finished.
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default 0x5614 0 ReferencingVelocity INT32 rw Y 1000…INT32 1000
DrivePositionControl
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x561A 0 ReferencingForce INT16 rw Y INT16 0
DrivePositionControl
Index Sub-index Parameter name Data type Access
Persis-
6.6.3.4 Object 0x5617: Z pulse trigger
In the second step of the reference run, the parameter <ZPulseTrigger> (0x5617) will enable the Z pulse to trigger the reference position of the encoder. If <ZPulseTrigger> (0x5617) = 0, the Z pulse is ignored and will not be dedected.
6.6.3.5 Object 0x5611: Z pulse detected
This flag will be set when the Z pulse will appear in the second step of the reference run. It will be reset on start of the reference run while the <DeviceMode> (0x6042) is switched to 4 (reference mode).
6.6.3.6 Object 0x5618: Z pulse clear
This parameter is implemented for compatibility reasons to old software. It will clear the internal Z pulse latch which is done automatically in the actual software.
6.6.3.7 Object 0x5610: Z pulse enable
If this flag is set, the valve is waiting for the next Z pulse. When the Z pulse appears, the predefined position <ZPulseSet> (0x5612) is copied to the <EncoderValue> (0x5613) and <ZPulseEnable> (0x5610) is reset to indicate the successful referencing. Only if the <DeviceMode> (0x6042) is switched to 1 or 2 (setpoint input via bus or locally).
6.6.3.8 Object 0x5612: Z pulse set
This is a predefined position. It will be copied to the <EncoderValue> (0x5613), if a Z pulse appears while <ZPulseEnable> (0x5610) is set. Only if the <DeviceMode> (0x6042) is switched to 1 or 2 (setpoint input via bus or locally).
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x5617 0 ZPulseTrigger UINT8 rw N 0…1 0
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x5611 0 ZPulseDetected UINT8 rw N 0…1 0
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x5618 0 ZPulseClear UINT8 rw N 0…1 0
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
6.6.4 SSI encoder
The SSI encoder sends an absolute position to the valve. For communication the valve needs two parame- ters, the <BitSize> (0x6243) and <BitRate> (0x561F).
6.6.4.1 Object 0x5620: Master slave
Only the SSI master interface is supported.
Value description
6.6.4.2 Object 0x6243: Bit size
This parameter sets the number of bits which have to be sent to the valve (the size of the SSI telegram). It de- pends on the type of the transducer.
6.6.4.3 Object 0x561F: Bit rate
The <BitRate> (0x561F) is used to change the clock frequency for the transmission of the bits to the valve. It depends, i.e. on the length of the cable, the noise environment and the specification of the transducer.
Value description
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x5620 0 MasterSlave UINT8 rw N 0…1 1
<MasterSlave> Description Clock signal
0 Slave (not yet supported) From the encoder.
1 Master From the servo valve.
Table 51: Possible values of parameter <MasterSlave> (0x5620)
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x6243 0 BitSize UINT8 rw N 0…32 0
Drive_ActualValueConditioning
Index Sub-index Parameter name Data type Access
Persis-
tence Value range Default
0x561F 0 BitRate UINT8 rw Y 0…7 2
<BitRate> SSI clock frequency
0 5 MHz 1 2.5 MHz 2 1.25 MHz 3 625 kHz 4 312.5 kHz 5 156.25 kHz 6 78.125 kHz
6.6.4.4 Object 0x3252: SSI Error Count
The <SSIErrorCount> (0x3252) is used to delay the SSI Error for n SSI transmission cycles. Default: after 3 incorrect SSI transmission cycles, the SSI Error (fault reaction 44) will be thrown.