Basler Electric DGC-2020 - Manual (Page 438)

B-6 DGC-2020 Modbus
™ Communication
9400200990 Rev X
Long Integer Data Format (INT32)
The Modbus long integer data format uses two consecutive holding registers to represent a 32-bit data
value. The first register contains the low-order 16 bits and the second register contains the high-order 16
bits.
Example: The value 95,800 represented in long integer format is hexadecimal 0x00017638. This number
will read from two consecutive holding registers as follows:
Holding Register Value
K (Hi Byte) hex 76
K (Lo Byte) hex 38
K+1 (Hi Byte) hex 00
K+1 (Lo Byte) hex 01
The same byte alignments are required to write.
32-bit Bit-Mapped Parameter Mapping
The register arrangement for 32-bit bit-mapped parameters is illustrated in Figure B-1. The Alarm
Metering registers (44812/44813) are shown as an example. In this example, Bit 25 is set indicating an
Overcrank condition and Bit 17 is set indicating a Global Alarm.
Figure B-1. 32-Bit Bit-Mapped Parameter Mapping
The Alarm Metering register bits are defined as follows:
•
Bit 0 through Bit 16 = Not Used
•
Bit 17 = Global Alarm
•
Bit 18 = Auto Restart Failure
•
Bit 19 = Fuel Leak Detect
•
Bit 20 = Battery Charger Failure
•
Bit 21 = Transfer Fail
•
Bit 22 = Low Coolant Level
•
Bit 23 = ECU Shutdown
•
Bit 24 = Emergency Shutdown
•
Bit 25 = Overcrank
•
Bit 26 = Loss of ECU Comms
•
Bit 27 = Global Sender Fail
•
Bit 28 = Low Fuel Level
•
Bit 29 = Low Oil Pressure
•
Bit 30 = Hi Coolant Temp
•
Bit 31 = Overspeed
Floating Point Data Format
The Modbus floating point data format uses two consecutive holding registers to represent a data value.
The first register contains the low-order 16 bits of the following 32-bit format:
•
MSB is the sign bit for the floating-point value (0 = positive).
•
The next 8 bits are the exponent biased by 127 decimal.
•
The 23 LSBs comprise the normalized mantissa. The most-significant bit of the mantissa is
always assumed to be 1 and is not explicitly stored, yielding an effective precision of 24 bits.