How many characters can be holded by a string data type parameter example OAR MSG1 & MSG2 parmeters?In serial card if i configured number of values as 100 in dataset configuration then how much characters can be handled by that daatset
I think the answer is 200:
http://www3.emersonprocess.com/systems/support/bol1231/r_maximum_number_of_values_for_datasets.html
If the data type is string, the Serial Card reads one string from the serial device. The size of the string is defined by the Number of values field. The size is the number of values * 2. The default value for the number of values field is 1.
Serial device data type
DeltaV data type
Maximum number of values
Coils, Input Status
All except 32-bit signed and unsigned integer and floating point
100
32-bit signed and unsigned integer and floating point
50
Input Registers, Holding Registers
All data types
Diagnostics
17
http://www3.emersonprocess.com/systems/support/bol1231/r_serial_dataset_configuration.html
The String data type is only valid if the PLC data type is input registers or holding registers.
In reply to Youssef.El-Bahtimy:
As far as I can tell, a STRING type parameter can hold up to 124 characters. String parameters written from expressions are limited to 256 chars.
Like Youssef explains this is further limited to 200 because of the maximum serial dataset size. 200 chars can be quite a long operator request.
If possible, you could consider using an enumeration or named set instead and only send the integer over serial bus. Then on the receiving end, show the according string. In DeltaV named sets however, strings are limited even to 48 chars. So might not be usable in your case.