Open Issues

Opto Input Edge Trigger Bug Alert

Description:
SynqNet Option Card Opto I/O can cause a false trigger of Edge Triggered Functions.

Product Affected:
Kollmorgen S200 Servo Drive with SynqNet Option Card

Models Numbers Affected:
S20xx0-SRS
S20xx0-SDS

Severity:
Low - Many applications do not use the affected function

Versions:
Bug existed in versions prior to C0FE0036_0400_02_00.

Resolution:
The bug was fixed in SynqNet FPGA version 0x0400_02_00. There is a work around for older versions.

On the S200 SynqNet Option card, the J13 connector has four optically isolated digital inputs (pins 2-5). When the input command goes from LED current to no LED current, the output voltage rise time of the internal opto isolator is slow enough that the drive control logic might see multiple transitions instead of a clean edge. These potential extra transitions could last a few 10's of microseconds. The no LED current to LED current edge transition has a single clean edge detected by the drive control logic. So, for any use of these inputs that is level-sensitive and not edge-sensitive, or for applications that avoid LED current to no LED current transitions while looking for an edge, there will be no application problems. Currently J13; pin 5 (OInp4) is not configurable for an edge trigger, so it is not affected.

To illustrate the potential problem when using these opto inputs for edge detection, consider a homing routine. Assume that a Home switch is set up so that going from no opto LED current to opto LED current is the desired switch transition defining the Home location. Then, if the application starts homing with no LED, current homing will cleanly go to the first edge, turning ON the current LED. However, if homing starts with the LED current ON, there can be a problem. See the below sequence for details.

Application Drive Logic

Start:
Home Switch ON/ LED current Logic High

Motion engages Home switch:
LED current (OFF to ON) Logic sees High to Low to High to final Low rest state

Motion disengages Home switch:
LED current (ON to OFF) Logic sees a single Low to High transition

In the above sequence, if the Home routine was set up to trigger on the Low to High transition, the drive control logic would actually trigger on the motion engaging the switch and not on the further motion disengaging the switch.

FPGA, version 0x400_02_00 eliminates the false high speed edges detected on LED current to no LED current by filtering any pulse less than 50 microseconds. The work around with older SynqNet controller versions, is to avoid using edge triggered functions on the S200 Option card opto inputs or make sure that the application does not have an LED current to no LED current transition when the application needs to trigger OFF and there is no LED current to LED current edge. In other words, have the application trigger on the leading edge of the Home switch and not on a trailing edge.

For more information, see issue FP512 in the C0FE0036 FPGA Release Notes.