CAUTION The user must not turn start accept flags ON/OFF
3.2 Data Registers
3.2.1 Monitoring data area
The monitoring data area is used by the PCPU to store data such as the feed current value during positioning control, the real current value, and the number of droop pulses in the deviation counter.
It can be used to check the positioning control status using the sequence program.
The user cannot write data into the monitoring data area (with the exception of the travel value register).
For details on the delay time between a positioning device (input, internal relay, special relay) going ON or OFF and storage of data in the monitor data area, see APPENDIX 6 “Processing Times”.
(1) Feed current value register (D0+20n) ...Data from the PCPU to the SCPU (a) This register stores the target address output to the servo amplifier on the
basis of the positioning address/travel value designated in the servo program.
1) In fixed-pitch feed control, the travel value counted up from 0 after motion starts is stored.
2) In speed/position switching control, the current value counted up from the address when motion starts is stored.
However, the address at start time varies depending on the ON/OFF status of the feed current value update command (M3212+20n) at start time.
• M3212+20n: OFF...Resets the feed current value to 0 at start time.
• M3212+20n: ON...Not reset the feed current value at start time.
3) During speed control, "0" is stored.
(b) The stroke range check is performed on this feed current value data.
(2) Real current value register (D2+20n) ...Data from the PCPU to the SCPU (a) This register stores the current value attained in real travel (the feed current
value minus the droop pulses in the deviation counter).
(b) In the stopped status, the feed current value is equal to the real current value.
(3) Deviation counter value register (D4+20n)....Data from the PCPU to the SCPU This register stores the difference between the feed current value and the real current value.
(4) Minor error code register (D6+20n)... Data from the PCPU to the SCPU (a) This register stores the relevant error code (see Appendix 2.2) when a
minor error occurs.
If another minor error occurs, the previous error code is overwritten by the new error code.
(b) Minor error codes can be cleared by an error reset signal (M3207+20n).
(5) Major error code register (D7+20n)... Data from the PCPU to the SCPU (a) This register stores the relevant error code (see Appendix 2.3) when a
major error occurs.
If another major error occurs, the previous error code is overwritten by the new error code.
(b) Major error codes can be cleared by an error reset signal (M3207+20n).
3. POSITIONING SIGNALS
(6) Servo error code register (D8+20n) ...Data from the PCPU to the SCPU (a) This register stores the relevant error code (see Appendix 2.4) when a
servo error occurs.
If another servo error occurs, the previous error code is overwritten by the new error code.
(b) Servo error codes can be cleared by a servo error reset signal (M3208+20n).
(7) Zeroing second travel value register (D9+20n) ... Data from the PCPU to the SCPU
If the position at which motion stops in accordance with the travel value setting (see Section 7.21) after the proximity dog has been switched ON by a
peripheral device is not the zero point, the servo system CPU will initiate a second travel to the zero point. The travel value for travel to the zero point during this second operation is stored in this register (with no sign appended).
When the feedback pulse count of the motor connected is 131072 PLS, the value found by dividing the second travel value to home position by 10 is stored.
Note that in the case of a data set type zeroing operation, the data remains unchanged (the previous value stands).
(8) Travel value after proximity dog comes ON register
(D10+20n, D11+20n) ...Data from the PCPU to the SCPU (a) When a zeroing operation is performed, the travel value from the point
where the proximity dog comes ON to the point where the zeroing operation is completed is stored in this register (with no sign appended).
(b) In speed/position switching control, the travel value during position control is stored in this register (with no sign appended).
(9) Executed program number register (D12+20n) ... Data from the PCPU to the SCPU
(a) The program number of the program being executed is stored in this register when the SVST instruction is executed.
(b) In JOG operation and manual pulse generator operation, the values indicated below are stored in this register.
1) JOG operation... FFFF 2) Manual pulse generator operation ... FFFE 3) When the power is turned on ... FF00
(c) When either of the following is being executed by a peripheral device in the test mode, FFFD is stored in this register.
1) A zeroing
2) A position loop gain or position control gain 1 check in servo diagnosis.
(10) M-code register (D13+20n) ...Data from the PCPU to the SCPU (a) The M-code(Note) set for the executed servo program is stored in this
register when positioning starts. If no M-code is set for the servo program, the value stored is "0".
(b) If positioning is started by a means other than a servo program, the existing value does not change.
(c) The stored value changes to "0" at the leading edge of the PLC READY
3. POSITIONING SIGNALS
REMARK
(Note): See the following sections for details on M-codes and reading M-codes.
• M-code ...Section 8.2
• M-code reading ...Appendix 4.1
(11) Torque limit value register (D14+20n)...Data from the PCPU to the SCPU This register stores the value for the torque limit imposed on the servo system. The default value of 300% is stored in this register when the power to the servo system is turned on or at the leading edge of the PLC READY signal (M2000).
(12) Constant-speed control data set pointer (D15+20n) ... Data from the PCPU to the SCPU
This pointer is used in constant-speed control when specifying positioning data indirectly and substituting positioning data during operation.
It stores a "point" that indicates which of the values stored in indirect devices has been input to the PCPU when positioning is being repeated by using a repeat instruction (FOR-TIMES, FOR-ON, FOR-OFF).
Use this pointer in conjunction with the PLC set pointer (controlled by the user in the sequence program) - which indicates the extent to which the positioning data has been updated by the SCPU - to confirm which positioning data is to be updated.
The use of the data set pointer and PLC set pointer for constant-speed control is explained here using the example servo program below.
CPSTART2
Poins are set in the order FOR-TIMES
FOR-ON FOR-OFF NEXT
0, 1, 2, etc., starting from the head of the sequence defined by the following repeat instructions :
The input of positioning data to the PCPU on updating the positioning data in indirect devices D0 to D6 when 2-axes constant-speed control is executed using the servo program shown above is described overpage.
3. POSITIONING SIGNALS
[Input of positioning data to the PCPU]
(A)
Indirect device D 0
Data set pointer for constant-speed control
! Indicates the last positioning data input to the PCPU.
! Each time the positioning at a point is completed, the value increases by one.
PLC set pointer
! Indicates the last positioning data updated by the sequence program last time.
! The user controls this pointer in the sequence program.
Data updating in accordance with sequence program
Positioning data input to the PCPU at each point
Positioning execution point
SCPU PCPU
The internal processing for the operation shown above is described overpage.
3. POSITIONING SIGNALS
[Internal processing]
(a) On starting the operation, the positioning data of points 0 to 6 ((1) to (14)) is input to the PCPU.
At this time, the last point of the data to be input - which is point "6" - is stored in the data set pointer for constant-speed control.
The "6" stored in the data set pointer for constant-speed control indicates that updating of the positioning data stored in points 0 to 6 is possible.
(b) The positioning data of points 0 and 1 ((A) to (D)) is updated in accordance with the sequence program.
The last positioning data to be rewritten - which is the data of point "1" - is stored in the PLC set pointer (which must be controlled by the user in the sequence program). Updating of positioning data of points 2 to 6 (data (5) to (14)) remains possible.
(c) On completion of the positioning for point 0, the value in the data set pointer for constant-speed control is automatically incremented by one to "7".
At this time, the positioning data of point 0 ((1) to (2)) is discarded and the positioning data for point 7 ((15) to (16)) is input to the PCPU.
(d) Hereafter, each time the positioning for a point is completed, the positioning data shifts one place.
The positioning data that can be updated is the data after that indicated by the PLC set pointer: this is the data which has not yet been input to the PCPU.
Consequently, after completion of the positioning corresponding to point 3, even if the values stored in indirect devices D8 and D10 are updated by the sequence program, the point 2 positioning data that is input to the PCPU will not be updated and the second positioning will be executed using the unupdated data.
In other words, the data set pointer for constant-speed control is a pointer that indicates data that has not yet been input to the PCPU and can be updated by the sequence program.
POINT
Number of points that can be defined by a repeat instruction
• Create a subprogram to create at least eight points.
• If there are less than eight points and these include pass points with small travel values, the positioning at each point may be completed, and the data input to the PCPU, before the data has been updated by the sequence program.
• Create a sufficient number of points to ensure that data will not be input to the PCPU before the SCPU has updated the values in the indirect devices.
(13) Travel value change register (D16+20n, D17+20n) ... Data from the SCPU to the PCPU
This is the area used when the position control travel value is changed in speed/position switching control (see Section 7.14).
(14) Real current value when STOP is input register
(D18+20n, D19+20n) ...Data from the PCPU to the SCPU This register stores the real current value when a STOP signal is input from an external source.