Flowserve DDC-100 Modbus Direct-to-Host - Manual (Page 14)

22 DDC-100 Direct-to-Host Programming Guide FCD LMAIM4019-00 FCD LMAIM4019-00 DDC-100 Direct-to-Host Programming Guide 23
Second Command
Query B30600001A009978
Response B30600001A009978
Second Command Message Breakdown
Query Response
B3 Slave (Field Unit) Address B3
Slave (Field Unit)
Address
06 Function 06 Function
00 Register Address Hi 00 Register Address Hi
00 1 Register Address Lo 00 Register Address Lo
1A Force Data Hi 1A Preset Data Hi
00 2 Force Data Lo 00 Preset Data Lo
9978 Error Check (CRC) 9978 Error Check (CRC)
Note 1: 0000h equals Register Address 40001 (field unit register 1, command register).
Note 2: 1A00h equals 6656.
Example of single register write “move-to” command
This command allows a Host to issue the “move-to” command with a single write utilizing the
Modbus function code 06. Register 1 will be used to complete this command.
Rules for utilizing this command:
• Field unit scaling must be configured for 0-100.
• To use the hexadecimal method of determining a single write “move-to” command, 0x4B is
always placed into the Hi Byte of Register 1.
• The desired position value is always placed into the Lo Byte of Register 1.
To move the actuator to a position of 50%, place the value 0x4B in the high byte and the value of
0x32 (50 decimal) into the low byte.
Example:
Hex format: 0x4B32
To use the decimal method of determining a single write “move-to” command, add the desired
position value to 19200.
Example:
Desired position: 50%
19200 + 50 = 19250
Example of single write “move-to” command
Move an actuator at address 1 to 50% of open by writing the value of 19250 (0x4B32) to the field
unit 40001 register. The actuator will then move to a position of 50% open.
Example
Query: 010600004B323EEF
Response: 010600004B323EEF
Message Breakdown
Query Response
01 Slave Address 01 Slave Address
06 Function 06 Function
00 Starting Address Hi 00 Starting Address Hi
00 Starting Address Lo 00 Starting Address Lo
4B Preset Data Hi 4B Preset Data Hi
32 Preset Data Lo 32 Preset Data Lo
3EEF Error Check (LRC or CRC) 3EEF Error Check (LRC or CRC)
3.2.7 Modbus Function Code 08 (Diagnostics)
This function code provides a series of tests for checking the communication system between
the Host and field units (slaves), or for checking various error conditions within the field unit.
This function code uses a two-byte subfunction code field in the query to define the type of test
to be performed. The field unit echoes both the function code and subfunction code in a normal
response. It does not affect the field unit in any way. If this exchange is successful, then the
communication is successful.
A listing of the supported diagnostic two-byte subfunction codes is given in Table 3.8.
Example
Request a loopback (return query data) from the field unit at network address 3.
Query 030800000000E1E9
Response 030800000000E1E9
Message Breakdown
Query Response
03 Slave (Field Unit) Address 03 Slave (Field Unit) Address
08 Function 08 Function
00 Subfunction Hi 00 Subfunction Hi
00 Subfunction Lo 00 Subfunction Lo
00 Data Hi 00 Data Hi
00 Data Lo 00 Data Lo
E1E9 Error Check (CRC) E1E9 Error Check (CRC)
Table 3.8 – Diagnostic Codes Supported by the DDC-100 Field Unit
Code Name
00 Return Query Data
01 Restart Communication Option
02 Return Diagnostic Register1
03 Change ASCII Input Delimiter
04 Force Listen-Only Mode
10 (0A Hex) Clear Counters and Diagnostics Register
11 (0B Hex) Return Bus Message Count
12 (0C Hex) Return Bus Communication Error Count
13 (0D Hex) Return Bus Exception Error Count
14 (0E Hex) Return Slave Message Count
Note 1: Contains DDC-100 Field Unit diagnostic information. For engineering use only.