DeltaV Serial Card
78 views
Skip to first unread message
Tim Alosi
Feb 11, 2009, 8:37:00 PM2/11/09
to drde...@googlegroups.com
Displaying all 8 posts by 6 people.
Post #1
Glen Fry wroteon January 31, 2009 at 2:26pm
What limitation does the Delta V serial card have ?
I am referring to the amount of devices that can be connected to the serial card. Thank you
I am referring to the amount of devices that can be connected to the serial card. Thank you
Post #2
You wroteon February 1, 2009 at 1:24pm
Each port supports 16 datasets. A data set is a group of contiguous registers in a single direction (read by DeltaV or written by DeltaV) to a single device.
So you question has a few answers ... if you want one group of registers from each device, you can communicate to 16 per port. If you want one read and one write per device, you can communicate to 8 devices.
Tim
So you question has a few answers ... if you want one group of registers from each device, you can communicate to 16 per port. If you want one read and one write per device, you can communicate to 8 devices.
Tim
Post #3
Mark Schuler (3M) wroteon February 9, 2009 at 2:11pm
Hello Tim,
I have a question concerning editing serial information for online processes. I am using one control module to accomodate all the serial data coming from a Modicon PLC. The serial data is coming across via a number of devices and a larger number of datasets. If I add a serial point to a particular dataset and this point becomes part of the control module, will I be able to download that control module without interrupting the control system? Or will I encounter a brief loss of data/communication when the download takes place?
I have a question concerning editing serial information for online processes. I am using one control module to accomodate all the serial data coming from a Modicon PLC. The serial data is coming across via a number of devices and a larger number of datasets. If I add a serial point to a particular dataset and this point becomes part of the control module, will I be able to download that control module without interrupting the control system? Or will I encounter a brief loss of data/communication when the download takes place?
Post #4
Mart Berutti (St. Louis, MO) wrote23 hours ago
Mark,
If you do not make a change to the serial card dataset definition, but only reference the register from a module and then download the module, you will only affect the control module. The communication through the serial card with the PLC is not affected.
A trick to add to Tim's post above. If you make the dataset direction output and select the IO readback box in the dataset configuration you can use the same dataset to read and write values between the PLC and DeltaV. This is commonly done with holding registers (4xxxx).
You can do the same thing with the Virtual IO Module and the Modbus TCP/IP Driver (shameless plug :)).
If you do not make a change to the serial card dataset definition, but only reference the register from a module and then download the module, you will only affect the control module. The communication through the serial card with the PLC is not affected.
A trick to add to Tim's post above. If you make the dataset direction output and select the IO readback box in the dataset configuration you can use the same dataset to read and write values between the PLC and DeltaV. This is commonly done with holding registers (4xxxx).
You can do the same thing with the Virtual IO Module and the Modbus TCP/IP Driver (shameless plug :)).
Post #5
Dave Tozer (Indianapolis, IN) wrote22 hours ago
I noticed that the PDS for the serial interface card was recently updated. Can someone fill me in on the latest changes to the card or general reason for the data sheet update? Thanks.
Post #6
Andre Dicaire (Austin, TX) wrote2 hours ago
Dave,
The PDS was updated primarily for its keyword search terms. I also clarified the use of "marshalling modules" where a user could bring an entire data set into a singl module and be charged a single DST for the lot. There were no technical changes to the card or commercial changes.
I stated that when integrating PLC serial data directly in control modules, the data set registers can be referenced directly rather than through a marshalling module. This creates a more straight forward data path, eliminating data latency created with the Marshalling module.
Of course the marshalling module could be run at 100 ms to minimize latency, but that consumes CPU. Still, the DST cost may drive a user to use the marshalling module for control. That is a system design choice.
One issue with a marshalling module is that if downloaded, depending on the module configuration and DeltaV version, the module may not have updated its registers before another module reads one, and it could read a default value. Similary, the module may write to the Dataset before all the inputs have been updated from the control modules. If used for control, the marshalling modules should not be downloaded while the process is running.
So I thought the PDS should differentiate between direct and marshalled Dataset IO, and I positioned the Marshalling module solution for data acquisition. Direct references would be better suited for control level communication.
Andre
The PDS was updated primarily for its keyword search terms. I also clarified the use of "marshalling modules" where a user could bring an entire data set into a singl module and be charged a single DST for the lot. There were no technical changes to the card or commercial changes.
I stated that when integrating PLC serial data directly in control modules, the data set registers can be referenced directly rather than through a marshalling module. This creates a more straight forward data path, eliminating data latency created with the Marshalling module.
Of course the marshalling module could be run at 100 ms to minimize latency, but that consumes CPU. Still, the DST cost may drive a user to use the marshalling module for control. That is a system design choice.
One issue with a marshalling module is that if downloaded, depending on the module configuration and DeltaV version, the module may not have updated its registers before another module reads one, and it could read a default value. Similary, the module may write to the Dataset before all the inputs have been updated from the control modules. If used for control, the marshalling modules should not be downloaded while the process is running.
So I thought the PDS should differentiate between direct and marshalled Dataset IO, and I positioned the Marshalling module solution for data acquisition. Direct references would be better suited for control level communication.
Andre
Post #7
Glen Fry wrote54 minutes ago
Can a Delta V serial card handle communication with 16 Variable Frequency Drive units without problems?
Post #8
You wrote29 seconds ago
Glen,
Assuming that the communication can be done to each drive with a single data set, the answer is Yes ... I would expect round trip for 16 data sets of 10 registers or less to be about 1 second assuming a baud rate of 19200 or 38400
Assuming that the communication can be done to each drive with a single data set, the answer is Yes ... I would expect round trip for 16 data sets of 10 registers or less to be about 1 second assuming a baud rate of 19200 or 38400
Reply all
Reply to author
Forward
0 new messages