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VIPA System 300S
6.4.4.7
FC 07 - Read Exception State
6.4.4.8
FC 08 - Loop Back Diagnostic Test
HB130 | CP | 341-1CH01 | en | 18-40
n
This function code serves to read 8 event bits of the connected slave.
n
The start bit number of the event bit is determined by the connected slave and does
not therefore have to be specified by the user program.
DB SEND source
Address
Name
+0.0
ADDR
+1.0
FUNC
DB RCV destination
Address
Name
+0.0
data[1]
n
The driver enters the individual bits of the reply message into the high byte in the des-
tination DB "data[1]".
n
The low byte of "data[1]" remains unchanged.
n
This function serves to check the communications connection.
n
The slave must return the request message to the master unchanged.
n
The reply message is not entered in the RCV destination DB.
DB SEND source
Address
Name
+0.0
ADDR
+1.0
FUNC
+2.0
diag_code
+4.0
test_value
n
diag_code
–
The only permissible value for the parameter diag_code is 0000.
n
test_value
–
Any 16bit value may be used as test_value.
Communication protocols
Modbus > Modbus Master - Function codes
Type
Comment
BYTE
Slave address
BYTE
Function code
Type
Comment
WORD
Data
Type
Comment
BYTE
Slave address
BYTE
Function code
WORD
Diagnostic code
WORD
Test value
63
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