9440300990 Rev J
237
DECS-250
PROFIBUS Communication
PROFIBUS Communication
On units equipped with the PROFIBUS communication protocol (style xxxxxxP), the DECS-250 sends
and receives PROFIBUS data through a DB-9 port located on the right side panel.
Refer to the
Communication
chapter for PROFIBUS communication settings in BESTCOMS
Plus
®
and the
Terminals and Connectors
chapter for wiring.
The DECS-250 utilizes PROFIBUS DP (Decentralized Peripherals) to operate sensors and actuators via
a centralized controller in production (factory) automation applications.
Per IEC 61158, PROFIBUS, consists of digitized signals transmitted over a simple, two-wire bus. It is
intended to replace the industry-standard, 4 to 20 mA signal used in the transmission of system
parameters. PROFIBUS expands the amount of information shared by system devices and makes the
exchange of data faster and more efficient.
Data Types
Float/UINT32
Parameters listed in Table 39 as Float or UINT32 types are “Input 2 word” (4 byte) parameters. The
Network Byte Order setting allows the byte order of these parameters to be set to MSB first or LSB first.
This setting can be found by using the following navigation paths.
BESTCOMSPlus
®
Navigation Path:
Settings Explorer, Communications, Profibus Setup
HMI Navigation Path:
Settings, Communications, Profibus Setup
UINT8
Parameters listed in Table 39 as UINT8 types are bit-packed binary data. This allows transmission of up
to eight single-bit parameters in each byte of data. When configuring an instance of UINT8 type
parameters, the data type is “Input 1 byte” and the size is determined by the number of parameters in the
instance divided by eight, rounding up to the next integer. Table 34 illustrates the sizes of the UINT8
cyclic data instances.
Table 34. Instance Data Size Calculation
Instance Number
Number of Parameters
in the Instance
Number of Parameters
Divided by Eight
Total Data Size
6
5
0.625
1 byte
7
7
0.875
1 byte
8
5
0.625
1 byte
9
6
0.75
1 byte
10
16
2
2 bytes
11
12
1.5
2 bytes
12
8
1
1 byte
Within these instances, the data is packed in the order listed in Table 39. The first item is the lowest bit of
the first byte. If there are unused bits, they are filled with a value of zero. Parameters of UINT8 type are
not affected by the DECS-250 Network Byte Order setting. The examples, below, show the bit packing
order for instances 8 (Controller Status Cyclic) and 11 (Local Contact Outputs Cyclic).
Example 1: Bit Packing Order for Instance 8
The total data size of Instance 8 is one byte. Table 35 shows the parameters of instance 8 as they appear
in Table 39. The first parameter in instance 8, with key name DECSCONTROL IN AVR MODE, is
represented by the lowest bit in the byte (bit 0). Bit 1 represents the next parameter with key name
Summary of Contents for DECS-250
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Page 6: ...iv 9440300990 Rev J Revision History DECS 250 ...
Page 16: ...xiv 9440300990 Rev J Contents DECS 250 ...
Page 20: ...4 9440300990 Rev J Introduction DECS 250 ...
Page 28: ...12 9440300990 Rev J Power Stage DECS 250 ...
Page 32: ...16 9440300990 Rev J Voltage and Current Sensing DECS 250 ...
Page 40: ...24 9440300990 Rev J Synchronizer DECS 250 ...
Page 52: ...36 9440300990 Rev J Auxiliary Control DECS 250 ...
Page 56: ...40 9440300990 Rev J Contact Inputs and Outputs DECS 250 ...
Page 84: ...68 9440300990 Rev J Limiters DECS 250 ...
Page 114: ...98 9440300990 Rev J Power System Stabilizer DECS 250 Figure 96 PSS Parameter Settings ...
Page 124: ...108 9440300990 Rev J Stability Tuning DECS 250 ...
Page 126: ...110 9440300990 Rev J Mounting DECS 250 Figure 103 Overall and Projection Mounting Dimensions ...
Page 127: ...9440300990 Rev J 111 DECS 250 Mounting Figure 104 DECS 250 Escutcheon Plate Dimensions ...
Page 198: ...182 9440300990 Rev J Timekeeping DECS 250 ...
Page 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
Page 304: ...288 9440300990 Rev J Maintenance DECS 250 ...
Page 316: ...300 9440300990 Rev J Specifications DECS 250 ...
Page 334: ...318 9440300990 Rev J Analog Expansion Module DECS 250 ...
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