GE EP-5261 User Manual page 18

Serial communication module
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18
GFK-2992B
To enable MODBUS data access, a User Defined Types MBM_Data must be imported.
To use the variables, an instance of this UDT must be built.
Every data transfer on the bus is initiated and controlled by the master. A high level on the input varible xMODfcStrobe
starts the job, and its function is determined by the function code entered at the input variable usiMODfc.
Communication with the MODBUS station, for which an address has been parameterized on the input variable
usiMODslaveAdr, is accepted. Depending on the function code, the MODBUS input parameters are interpreted as listed
in the following table.
Function
uiMODdatOff
Code
FC 1
Coil source offset in slave
Input source offset in
FC 2
slave
Holding register source
FC 3
offset in slave
Input register source
FC 4
offset in slave
FC 5
Coil target offset in slave
Holding register target
FC 6
offset in slave
FC 8
---
FC 15
Coil target offset in slave
Holding register target
FC 16
offset in slave
Buffers warMODRegister and xarMODCoil are always Read or Written by the master from the first index (MODBUS to 1).
The MODBUS diagnostic outputs usi_MODslaveAdrDone, usiMODfcDone, uiMODdatOffDone, and uiMODdatNrDone,
always mirror the communication state during a malfunction, meaning they acknowledge the respective inputs or
provide information concerning the content of the slave response. With function codes 5, 6 and 8, uiMODdatNrDone
describes the written value. The output xMODtransActive is TRUE during execution, until the slave response is received.
After the job has been completed, the output returns to FALSE and xMODtransOk is set to a value of 1 if no telegram
fault, protocol fault, data fault, or other communication fault has occurred. During a fault, xMODtransOk remains at
FALSE and the fault is described with the usiMODfailCode exception code. If the slave does not answer within the set
tMODtimeOut timeout threshold, an error message is generated. The outputs are refreshed each time a new job is
started.
uiMODdatNr
Number of requested
coils
Number of requested
inputs
Number of requested
registers
Number of requested
registers
---
---
---
Number of coils to be sent
Number of registers to be
sent
For public disclosure
RSTi-EP Slice I/O Serial Communication Module
warMODRegister
---
---
Holding register target
buffer in master
Input register target
buffer in master
---
Register value in index [1]
Test value in index [1]
---
Holding register source
buffer in master
xarMODCoil
Coil target buffer in
master
Input target buffer in
master
---
---
Coil value in index [1]
---
---
Coil source buffer in
master
---

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