Rockwell Automation 2711P Creating Modbus Applications - Manual (Page 61)

61 Publication 2711P-UM002B-EN-P - March 2007
Appendix
A
Data Types
This appendix describes valid data types for creating tags. This
information is also available in the Modbus driver online help in
KEPServer Enterprise.
Data Types
Description
(2)
(2) Not available for Modbus ASCII protocol.
Boolean Single bit
Word Unsigned16 bit value
bit 0 is the low bit
bit 15 is the high bit
Short Signed16 bit value
bit 0 is the low bit
bit 14 is the high bit
bit 15 is the sign bit
Dword Unsigned 32 bit value
bit 0 is the low bit
bit 31 is the high bit
Long Signed 32 bit value
bit 0 is the low bit
bit 30 is the high bit
bit 31 is the sign bit
BCD Two byte packed BCD
Value range is 0 - 9999.
Behavior is undefined for values beyond this range.
LBCD Four byte packed BCD
Value range is 0 - 99999999.
Behavior is undefined for values beyond this range.
Float 32-bit floating point value.
The driver interprets two consecutive registers as a
floating-point value by making the second register the high
word and the first register the low word.
Float Example: If register 40001 is specified as float, bit 0 of
register 40001 would be bit 0 of the 32-bit word, and bit 15 of
register 40002 would be bit 31 of the 32-bit word.
String
(1)
(1)
The descriptions assume first word low data handling of 32-bit data types.
Null terminated ASCII string
Supported on Modbus Model, includes HILo LoHi byte order
selection.
Modbus Serial
8 byte and 16 byte Omni Flow Computer string data