Question:
What should be considered when migrating 9400 applications using Digital Frequency to an i950 solution or in a mixed setup?
Answer:When retrofitting from the 9400 to the i950, the coupling cables can be reused because the pin assignments of the connectors are the same. In addition, a 9400 can be connected to an i950 (and vice versa) via the digital frequency module. However, the frequency limit must be observed (9400 = 500 kHz, i950 = 2 MHz), which must be specified in the application feedback.
Question:What are the typical delay times when using Lenze TAs in combination with Digital Frequency?
Answer:
The following table shows the measured reference values for dead time compensation in different Master-Slave combinations:
| System | Delay Time in Application |
| i950 Master - i950 Slave | 2,63 ms |
| i950 Master - 9400 Slave | 1,69 ms |
| 9400 Master - 9400 Slave | 2,91 ms |
| 9400 Master - i950 Slave | 3,84 ms |
Question:
How can these delay times be compensated in i950 in comparison to 9400?
Answer:
The dead time can be compensated for in the i950 master using the 0x500A:67/68 parameters. When the 9400 is used as the master, the L_SdDelayComp block must be inserted in the FB Editor before the setpoint value is passed on to the application in order to fully compensate for the dead time.
For compensation in i950, there are two modes to choose from in 0x500A:67: “Automatic for Setpoints [1]” and “Manual (Offset in Sub 68) [3].” The automatic mode relates to the delay time that occurs during setpoint transmission via the onboard EtherCAT system bus and is therefore unsuitable for compensating for the delay time with digital frequency.
In manual mode, the delay time is explicitly set via 0x500A:68. If a negative time value is specified, the setpoint is delayed by that amount of time. This “setpoint delay” method therefore requires configuration in the master and applies to all slave drives in the network. Another method of compensation would be setpoint extrapolation. This can be achieved by specifying the compensation time with a positive sign. This parameterization is therefore performed in all slaves. This sign rule also applies to the 9400 in conjunction with the L_SdDelayComp module.
As a general rule, a compensation in Slave is generally not recommended, as extrapolation effects might lead to inaccuracies in the signal.
