busarider29
Lifetime Supporting Member
This, among many other reasons, is why we prefer Beckhoff platform over anything else.
The problem with load cell "controller" or using amplifier modules to convert your load cell signal to an analog signal that your PLC can use with standard analog input is that you lose accuracy with that method, there are propagation delays, it's more expensive, you've made it more complicated, and last but certainly not least the signal data coming out of the load cell amplifier is not highly synchronized with the PLC. "Highly synchronized" to me is within 2 digit microseconds. But.....these are the kinds of rocky and pot-hole riddled roads you're continually forced to travel on in AB world. I know because I traveled many miles on those roads.
In Beckhoff world, the roads traveled are beautifully paved, with barely a bump in the road every now and then.
For instance, with your application using Beckhoff platform I would simply use any one of the following and be done.
EL3356-0010
Standard bridge input, 1-channel, 10 ks/S sampling frequency. Does not have "over-sampling" technology so sampling is only as fast as your PLC scan time with this module. To get full 10 ks/S sampling from it, we just have it scanned via a 100 microsecond task.
ELM3502-0030
High speed, 2-channel bridge module. As high as 20 ks/S/ch sampling frequency with "over-sampling" technology. Many features built in and can configure - filtering, sampling frequency, scaling, etc. Use for high precision measurement applications where accuracy and high sampling frequency are of utmost importance. If you use National Instruments hardware for such applications, this module could potentially replace that. We have several of these in a few machines. I love them for the aforementioned reasons, plus it has over-sampling tech, meaning I can evaluate the full 20k samples per second data from it in the PLC with even a slow scan time of only say, 10ms. The PLC processor likely loves me for this!
EPP3504-0023
4-channels, 10 ks/S/ch sampling frequency, over-sampling technology, IP20. Meant to be installed/mounted outside of the control cabinet, near or at the measurement location. Power-over-EtherCAT. one cable technology. We have one of these on one of our new testing machines. Love it for obvious reasons.
EP3356-0022
Similar to the above, but 1-channel.
Configuration can be as simple and easy as you want it to be. Grab your load cell (or strain gauge) data sheet, enter the mV/V value in the appropriate field in the TwinCAT software, enter the max nominal load of the load cell, and you're done. It's now fully integarated and part of the control system and load cell data is highly synchronized (within 2-digit microseconds) with all other process data.
The problem with load cell "controller" or using amplifier modules to convert your load cell signal to an analog signal that your PLC can use with standard analog input is that you lose accuracy with that method, there are propagation delays, it's more expensive, you've made it more complicated, and last but certainly not least the signal data coming out of the load cell amplifier is not highly synchronized with the PLC. "Highly synchronized" to me is within 2 digit microseconds. But.....these are the kinds of rocky and pot-hole riddled roads you're continually forced to travel on in AB world. I know because I traveled many miles on those roads.
In Beckhoff world, the roads traveled are beautifully paved, with barely a bump in the road every now and then.
For instance, with your application using Beckhoff platform I would simply use any one of the following and be done.
EL3356-0010
Standard bridge input, 1-channel, 10 ks/S sampling frequency. Does not have "over-sampling" technology so sampling is only as fast as your PLC scan time with this module. To get full 10 ks/S sampling from it, we just have it scanned via a 100 microsecond task.
ELM3502-0030
High speed, 2-channel bridge module. As high as 20 ks/S/ch sampling frequency with "over-sampling" technology. Many features built in and can configure - filtering, sampling frequency, scaling, etc. Use for high precision measurement applications where accuracy and high sampling frequency are of utmost importance. If you use National Instruments hardware for such applications, this module could potentially replace that. We have several of these in a few machines. I love them for the aforementioned reasons, plus it has over-sampling tech, meaning I can evaluate the full 20k samples per second data from it in the PLC with even a slow scan time of only say, 10ms. The PLC processor likely loves me for this!
EPP3504-0023
4-channels, 10 ks/S/ch sampling frequency, over-sampling technology, IP20. Meant to be installed/mounted outside of the control cabinet, near or at the measurement location. Power-over-EtherCAT. one cable technology. We have one of these on one of our new testing machines. Love it for obvious reasons.
EP3356-0022
Similar to the above, but 1-channel.
Configuration can be as simple and easy as you want it to be. Grab your load cell (or strain gauge) data sheet, enter the mV/V value in the appropriate field in the TwinCAT software, enter the max nominal load of the load cell, and you're done. It's now fully integarated and part of the control system and load cell data is highly synchronized (within 2-digit microseconds) with all other process data.
