Peter Nachtwey
Member
We have added a new feature to our latest motion control product. Our new product can do EthernetI/P I/O or implicit messaging at 1 millisecond intervals. However, just because we can doesn't mean we should. Our experience with our older product showed us that most people used RPIs in the 10 to 20 millisecond range because the ENBT card couldn't go any faster and the Ethernet starts having too many collisions.
There is no need to change parameters that fast. Anything that needs to happen that fast can be done inside the motion controller faster and in a more deterministic way than in the PLC.
I say 5 millisecond RPI is a realistic minimum even if we can go faster. First, can the PLC maintain a scan rate faster than 5 milliseconds. Second, given the Ethernet scan is asynchronous to the PLC scan is the effective scan rate even longer? Third, will the networks be capable of these higher rates? Fourth, will the EN2T card be capable of servicing the motion controllers and the HMIs and I/O. Fifth, any position feedback data coming from the PLC will be asynchronous so it would not be directly useful without filtering.
Has anybody used a RPI less than 5 millisecond? For what?
Note, the controller doesn't really need except to tell the controller when to start. The controller has its own program, memory and I/O so this isn't like the M02AE or M02AS where coarse updates are required.
A second question. How many I/O connections do you normally have to a EthernetI/P device.
Experiences wanted. We find the forum to be a valuable resource. Thanks.
BTW, we are still going round and round on the pass word protection issue I asked about last month. It sounds simple but.... In true Delta fashion everything is over anal_yzed. I want to scream. Back in the dark ages I would just do it.
There is no need to change parameters that fast. Anything that needs to happen that fast can be done inside the motion controller faster and in a more deterministic way than in the PLC.
I say 5 millisecond RPI is a realistic minimum even if we can go faster. First, can the PLC maintain a scan rate faster than 5 milliseconds. Second, given the Ethernet scan is asynchronous to the PLC scan is the effective scan rate even longer? Third, will the networks be capable of these higher rates? Fourth, will the EN2T card be capable of servicing the motion controllers and the HMIs and I/O. Fifth, any position feedback data coming from the PLC will be asynchronous so it would not be directly useful without filtering.
Has anybody used a RPI less than 5 millisecond? For what?
Note, the controller doesn't really need except to tell the controller when to start. The controller has its own program, memory and I/O so this isn't like the M02AE or M02AS where coarse updates are required.
A second question. How many I/O connections do you normally have to a EthernetI/P device.
Experiences wanted. We find the forum to be a valuable resource. Thanks.
BTW, we are still going round and round on the pass word protection issue I asked about last month. It sounds simple but.... In true Delta fashion everything is over anal_yzed. I want to scream. Back in the dark ages I would just do it.