170 • MODBUS Functions
Internal Variables
6.5.5 Constant Registers
The following registers contain constants, which can be used to test communication with the master:
Register address 0x2000 (MODBUS Address 408193)
Value |
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Zero, GP_ZERO |
Access |
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Read |
Description |
|
Constant with zeros |
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Register address 0x2001 (MODBUS Address 408194) |
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Value |
|
Ones, GP_ONES |
Access |
|
Read |
Description |
|
Constant with ones. Is –1 if this is declared as "signed int" or MAXVALUE if |
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it is declared as "unsigned int". |
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Register address 0x2002 (MODBUS Address 408195) |
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Value |
|
1,2,3,4, GP_1234 |
Access |
|
Read |
Description |
|
This constant value is used to test the Intel/Motorola format specifier. If the |
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master reads a value of 0x1234, then with Intel format is selected – this is the |
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correct format. If 0x3412 apears, Motorola format is selected. |
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Register address 0x2003 (MODBUS Address 408196) |
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Value |
|
Mask 1, GP_AAAA |
Access |
|
Read |
Description |
|
This constant is used to verify that all bits are accessible to the fieldbus |
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master. This will be used together with register 0x2004. |
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Register address 0x2004 (MODBUS Address 408197) |
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Value |
|
Mask 1, GP_5555 |
Access |
|
Read |
Description |
|
This constant is used to verify that all bits are accessible to the fieldbus |
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master. This will be used together with register 0x2003. |
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Register address 0x2005 (MODBUS Address 408198) |
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Value |
|
Maximum positiv number, GP_MAX_POS |
Access |
|
Read |
Description |
|
Constant in order to control arithmetic. |
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Register address 0x2006 (MODBUS Address 408199) |
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Value |
|
Maximum negativ number, GP_MAX_NEG |
Access |
|
Read |
Description |
|
Constant in order to control arithmetic. |
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Register address 0x2007 (MODBUS Address 408200) |
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Value |
|
Maximum half positiv number, GP_HALF_POS |
Access |
|
Read |
Description |
|
Constant in order to control arithmetic. |
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Register address 0x2008 (MODBUS Address 408201) |
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Value |
|
Maximum half negativ number, GP_HALF_NEG |
Access |
|
Read |
Description |
|
Constant in order to control arithmetic. |
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