ProSoft Technology 5204SE-MNET-PDPMV1 User Manual
Page 188
5204SE-MNET-PDPMV1 ♦ ProLinx Gateway
Reference
Modbus TCP/IP to PROFIBUS DP-V1 Pass-Through Master
User Manual
Page 188 of 235
ProSoft Technology, Inc.
December 22, 2009
Variable Name
Size/Type
Description
In - Length
1
8-bit Byte
This value specifies the number of valid acyclic read data
bytes returned by the slave.
In - ExtendedFault
1
16-bit Integer
Refer to Read Class 1 Acyclic Data Message Structure
(page 214)
In - Fault
1
16-bit Integer
Refer to Read Class 1 Acyclic Data Message Structure
(page 214)
In - AcyclicData[ ]
200-element
8-bit Byte
Array
This array will hold the actual acyclic read data bytes
returned by the slave.
In -
AcyclicReadActive
1
Single-bit
Boolean
The DFB will set this bit when the Modbus TCP/IP message
has been initiated and is being processed.
In - AcyclicReadError 1
Single-bit
Boolean
The DFB will set this bit when the Modbus TCP/IP response
is not successfully received. When this bit is set, it indicates
your control and sequencing logic should retry the
command.
In -
AcyclicReadSuccess
1
Single-bit
Boolean
The DFB will set this bit when the Modbus TCP/IP response
is successfully received and the PROFIBUS cyclic input
data variables have been updated.
NOTE: The MBP_MSTR function used on the Quantum platform has a lower data transfer limit
than the DATA_EXCH function for the M340 platform. As a result, on the Quantum platform, the
amount of data that can be transferred between a Quantum PAC and the ProLinx Gateway is 200,
8-bit bytes (100, 16-bit words) per message transaction.
This limit is more than enough for most PROFIBUS DP message telegrams. However, there are a
few PROFIBUS messages that could contain more data in the PROFIBUS response than can be
sent to the Quantum processor using the MBP_MSTR funcution for Modbus TCP/IP. It such
cases, the PROFIBUS data is truncated after the first 200-bytes, any PROFIBUS data beyond that
limit will not be sent to the Quantum, and the excess data will be lost.
The performance of this Read Class 1 Acyclic mailbox message may be affected by this limitation.
Please consult your device manufacture's documentation to see if any of your PROFIBUS DP
slave devices provide more than 200 bytes of acyclic read data per message.