Hach-Lange SC 100 - Manual (Page 49)

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Appendix A Modbus Protocol
A.1 Modbus Troubleshooting
A.2 sc100 Modbus Registers
Table 8: Troubleshooting
Problem Possible Causes Solution
No Modus Response
Baud rate, or stop bits does not match
settings of Modbus master
Verify sc100 settings match the Modbus master
settings.Verify Modbus master Parity setting is set to
None.
Bad RS232 or RS485 cable Replace/Repair cable
No or improper network biasing and
termination.
Check all network devices for termination or biasing
settings. Only the ends of the network should have
termination turned on and only one point on the network
should be providing biasing.
Slave Address incorrect or duplicate
address of another bus device.
Verify all addresses are unique and between 1 and 247.
Modbus Exception Response
Register not supported Verify register is supported
Data Type incorrect
Verify the requested register(s) Data Type matches the
Modbus Master Request e.g. do not access a Slave Float
value with a 2 byte Integer request. When requesting a
Float (2 registers/4 bytes), both registers must be
requested at the same time.
Table 9: sc100 Modbus Registers
Group Name Tag Name Register # Data Type Length R/W Description
Measurements
Calculated
Value
40001 Float 2 R
Value calculated from two sensor
measurements
Setup Language 40003
Unsigned
Integer
1 R/W Current System Language
Setup Date Format 40004
Unsigned
Integer
1 R/W
Current Data Display Format
(0 = DD/MM/YY; 1 = MM/DD/YY;
2 = DD-MM-YY; 3 = MM-DD-YY)
Setup
Error Hold
Mode
40005
Unsigned
Integer
1 R/W
Error Mode Hold State (0 = Hold outputs;
1 = Transfer outputs to predefined value)
Setup/Analog Output 1 Source 40006
Unsigned
Integer
1 R/W
Selects data source for this output
(0 = None; 2 = sensor; 4 = Calculation)
Setup/Analog Output 1 Sensor Select 40007
Unsigned
Integer
1 R/W
Selects sensor source when Source =
Sensor (0 = sensor1; 1 = sensor2)
Setup/Analog Output 1
Measurement
Select
40008
Unsigned
Integer
1 R/W
Selects measurement on the sensor
(0 = Meas1.. 3 = Meas4)
Setup/Analog Output 1 Type 40009
Unsigned
Integer
1 R/W
Selects output type
(0 = Linear output; 1 = PID control)
Setup/Analog Output 1 Transfer Value 40010 Float 2 R/W Sets the transfer value
Setup/Analog Output 1 Filter 40012
Unsigned
Integer
1 R/W
Sets the output filter value in seconds
(0 to 120 sec.)
Setup/Analog Output 1
0mA - 4mA
Select
40013
Unsigned
Integer
1 R/W
Selects 0mA/4mA for min output
(0 = 0mA; 1 = 4mA)
Setup/Analog Output
1/Linear
Min Setting 40014 Float 2 R/W Sets the min output value