Beckhoff KL2521 Series, Documentation

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Access from the user program
KL2521 36 Version: 2.1
5.4.2 KL2521-0010 - Process data exchange
Control byte in process data exchange (REG=0)
Bit 7 6 5 4 3 2 1 0
Name Reg_Access 0 SET_Z SET_T Cnt_Clr Go_Counter Ramp_Dis Freq_Sel
Bit Name Description
Bit 7 Reg_Access 0
bin:
Register communication inactive (process data exchange)
Bit 5 SET_Z Set output Z
Bit 4 SET_T Set output T
Bit 3 Cnt_Clr The counter value and eventually set overflow/underflow bits will be deleted by this bit This
can be done with edge control or level control (Feature.4).
Bit 2 Go_Counter If travel distance control is active (Feature.9), then a pre-set counter value is approached
when the bit is set.
Bit 1 Ramp_Dis The ramp function is disabled despite active Feature .5;
if the travel distance control is active it is aborted by this bit.
Bit 0 Freq_Sel Fast toggling of the base frequency (only if ramp function is deactivated)
0: Base frequency 1 (registers 36 / 37)
1: Base frequency 2 (registers 38 / 39)
The change of the base frequency requires a reset for activation.
Status byte in process data exchange (REG=0)
The status byte is transferred from the terminal to the controller.
Bit 7 6 5 4 3 2 1 0
Name Reg_Access Error Out_Z_ACK Out_T_ACK Overflow Underflow Ramp_Active Sel_Ack
Bit Name Description
Bit 7 Reg_Access 0
bin:
Acknowledgement for process data exchange
Bit 6 Error General error bit, included with overflow/underflow
Bit 5 Out_Z_ACK Output Z
Bit 4 Out_T_ACK Output T
Bit 3 Overflow This bit is set if the 16-bit counter overflows (65535 -> 0). It is reset when the counter ex-
ceeds one third of its measuring range (21845 -> 21846) or as soon as an underflow oc-
curs.
Bit 2 Underflow This bit is set if the 16-bit counter underflows (0 -> 65535). It is reset when the counter
drops below two thirds of its measuring range (43690 -> 43689) or as soon as an overflow
occurs.
Bit 1 Ramp_Active Ramp is currently being followed
Bit 0 Sel_Ack Confirms the change of base frequency.
5.4.3 Register communication
Register access via process data exchange
• Bit 7=1: Register mode
If bit 7 of the control byte is set, the first two bytes of the user data are not used for process data
exchange but written into the register set of the terminal or read from it.
• Bit 6=0: read, bit 6=1: write
Bit 6 of the control bytes is used to specify whether a register should be read or written.
◦ Bit 6=0 : a register is read without changing it. The value can be found in the input process
image.
◦ Bit 6=1 : the user data are written to a register. The process is complete once the status byte in
the input process image has returned an acknowledgment (see example).
• Bit 0 to 5: Address
The address of the register to be addressed is entered in bits 0 to 5 of the control byte.