Siemens SIMATIC S7 Manual page 35

Parameter Decl.
LENGTH IN/
OUT
WRITE_ IN/
READ OUT
General
Information
Range of Values
OPEN MODBUS / TCP communication via CP343-1 and 443-1
2XV9450-1MB00; Manual edition 4.3
Type Description
WORD Number of registers to be processed
(INPUT if in CLIENT mode, OUTPUT if in
SERVER mode)
Coils: reading function
writing function
Inputs: reading function
Holding Register: reading function
Input Register: reading function
BOOL INPUT if in CLIENT mode, OUTPUT if in
SERVER mode:
Write access
Read access
The parameters of the FB MODBUSCP can be divided into two groups:
•
Initialization parameters
•
Runtime parameters
Initialization parameters are evaluated only during the initial execution of the
function block MODBUSCP and taken over into the instance DB. They are
marked in the above table in the column "INIT" with "yes".
A modification of the initialization parameters during run mode has no impact.
After a modification of these parameters (e. g. during the test phase), the
instance DB must be initialized again via a STOP
CPU.
Runtime parameters can by modified during the cyclical operation. In the
mode "CP is client", it is not advisable to modify the input parameters while
a request is active. Wait with the next request and the change of the
parameters until the previous request ends with DONE_NDR or ERROR.
In the operation mode "CP is server", the output parameters may only be
evaluated when DONE_NDR is TRUE.
The output parameters are displayed dynamically, i.e. they are only
available for one PLC cycle. They have to be copied to an additional memory
area if you need to process them or to display the values in a VAT (STEP7
variable table).
For the range of values of the different parameters, CPU specific restrictions
must be taken into consideration.
Function Block MODBUSCP
writing function
Value range
1 to 2000
1 to 1968
1 to 2000
1 to 125
1 to 123
1 to 125
TRUE
FALSE
RUN transition of the
5-7
Init
no
no