X20 system modules • Counter modules • X20DC2395
X20 system User's Manual 3.10
823
4.11.14.12.7 SSI encoder interface
The module has 1 SSI encoders available, supported directly in the hardware. Two 24 V output channels are set
for the SSI encoder and cannot be changed. (See also 4.11.14.7.1 "Description of channel assignments")
When using the SSI encoder, the corresponding clock channel can be configured in the 4.11.14.12.4.1
"CfO_CFGchannel" register as "Channel-specific" and "Push/Pull".
SSI encoders
Channel number
Data channel
1
Clock channel
2
4.11.14.12.7.1 SSI event functions
The SSI encoder consists of an event function and an event input. The SSI cycle is started when an event is
received on this input.
Information:
The SSI event function is not linked to an event by default, i.e. SSI functions are disabled.
Two events are sent from the SSI encoder interface..
•
An "SSI valid" event is triggered immediately after the end of the SSI cycle if a new counter value is available.
•
The "SSI ready" event then shows when the monoflop time has expired (tp in SSI encoder timing diagram).
This is the earliest that the next SSI cycle can be started.
SSI encoder - Timing diagram
Clock
MSB
Data
SSI cycle
1
2
3
4
5
6
n
MSB
LSB
0
tp
SSI start event
SSI valid
SSI ready
Configure event ID for SSI
Name:
CfO_SSI1eventIDwr
This register holds the event ID that should start the SSI cycle. For a list of all possible event IDs, see 4.11.14.12.5.1
"List of event IDs"
Normally this register is set to network event 225 "AOSISOP"- This ensures that the new encoder position is
available at the next "I/O → Synchronous Frame" transfer. Check the SSI transfer time and the X2X cycle time,
because the SSI cycle must be completed within this time.
Data type
Value
Information
INT
192 to 7,233
ID of event function
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