CONTREX CX-1200 - Manual (Page 150)

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ALARMS
There are several monitored alarms built-in to the CX-1200. These alarms are included in the PLC Bit-
Map and can be used together or separately to activate an output or any other function that is available to
the PLC. To customize the alarms for your system, modify the PLC program to include the alarm bit. In
the PLC, Fb@0Spd (Bit 54) and RR@0Spd (Bit 53) are defaulted to DO-O, which functions as a indicator
for a “stop” condition. The PLC program defaults the HiSpdAlm (Bit 29) and LoSpdAlm (Bit 28) to Digital
Output 1 (DO-1) to serve as an Over/Under-Speed indicator. The remaining alarms are not included in the
default PLC program.
The PLC Bits that are influenced by the alarm Control Parameters are:
PLC
Bit Name
Description
53 RR@0Spd Ramped Reference < Zero Speed (CP-332) EU/Tm
54 Fb@0 Spd Fb EU/Tm <= Zero Speed (CP-332) EU/Tm
55 MxFbSpd Fb EU/Tm >= Max Fb Alm (CP-371) EU/Tm
56 MaxAclDcl FB Accel/Decel > Max Acl/Dcl (CP-372) EU/Sec 2
57 DrvNoResp Drive/Motor NOT responding for No Resp Time (CP-373)
Since the CX-1200 uses the Fb@0Spd (PLC Bit 54) for internal control, it is critical that you enter a valid
value for Zero Speed (CP-332). “F-Stop”, “H-Stop” and “R-Stop” use the Fb@0Spd (PLC Bit 54) to
determine when to force the DrvEnable (PLC Bit 51) to “0” (Off). If the feedback does not reach zero
speed as indicated by Fb@0Spd (PLC Bit 54) within 1/2 second, then the DrvEnable (PLC Bit 51) is reset
to “0” (Off).
The CX-1200 has an internal 1/2 second timer that functions with “R-Stop” “H-Stop” and “F-Stop”.
During “R-Stop” or “H-Stop” the timer engages only when the “R-Stop” or “H-Stop” ramp is completed.
However, during “F-Stop” the timer engages immediately. If the feedback slows to zero speed before 1/2
second expires, the DrvEnable (PLC Bit 51) will immediately reset to “0” for “R-Stop” and “F-Stop”. For
“H-Stop”, the DrvEnable bit will remain enabled if the feedback is from a quadrature encoder and if it is
supposed to stop with the loop closed.
Use Max Fb Alm (CP-371) to determine the state of the MxFbSpd (PLC Bit 55). The CX-1200 sets
MxFbSpd (PLC Bit 55) to “1” when Fb EU/Tm (MP-06) is greater than Max Fb Alm (CP-371).
Otherwise the CX-1200 resets MxFbSpd (PLC Bit 55) to “0”.
The change in the feedback speed is constantly being compared to Max Acl/Dcl (CP-372). If the
magnitude of the change in feedback speed is greater than Max Acl/Dcl, then set the MxAclDcl
(PLC Bit 55) to “1”. Otherwise the CX-1200 resets the bit to “0”.
If the CX-1200 is in “Run” and the CO Volts (MP-37) is greater than 1/8 the CO Max Volts (CP-271), the
RampedRef (MP-31) is greater than the Zero Speed (CP-332) and the feedback speed is less than Zero
Speed (CP-332) in excess of the time specified in NO Resp Time (CP-373), then the CX-1200 sets
DrvNoResp (bit 57) to “1”. Otherwise, the CX-1200 resets DrvNoResp (bit 57) to “0”.
Any number of problems is can be indicated when the CX-1200 sets DrvNoResp (bit 57) to “1”. For
example, it can indicate that neither the drive nor the motor is responding to a nonzero voltage input when
the CX-1200 has a nonzero speed reference while in “Run”. If this occurs when the motor is turning, it