B&B Electronics GW-7552 - Manual - Manual (Page 38)

GW-7552 PROFIBUS/MODBUS GATEWAY User Manual (Version 1.40, Apr/2012) PAGE: 38
* These error messages are not supported when the GW-7552 act as a Modbus
slave.
PS:
Data Error：
a. GW-7552 acts as a Modbus master
If the polling speed between the GW-7552 device and the Modbus slave is faster
than the data exchange rate between Profibus master and the GW-7552 then the
Profibus master will not get all the data from the Modbus slave and therefore a
diagnostic message (“Profibus lose input data”) will be send by the GW-7552 to
the Profibus master
b. GW-7552 acts as a Modbus slave
If the GW-7552 receives more telegram from the Modbus master than it
transmits to the Profibus master then a diagnostic message (“Profibus lose input
data”) will be send by the GW-7552 to the Profibus master.
c. When the GW-7552 receives a “data output command” (output byte 0) from
system setting module, and this command didn’t increased in order (ex: 0->1, 1-
>2,…, 255->0), the GW-7552 will think that it lose some output data of the
Profibus master and a diagnostic message (“Lose Profibus output data”) will be
send by the GW-7552 to the Profibus master.
4.6 I/O data exchange
The I/O data exchange is decided by Modbus type of the GW-7552 (please refer
section 4.3 The Configuration of the common parameters) between Profibus
master device and the GW-7552. Output data area of Profibus master device is
mapped into DO/AO memory of the GW-7552 and input data area of Profibus
master device is mapped into DI/AI memory of the GW-7552, when Modbus type
is master. In the other way, Output data area of Profibus master device is mapped
into DI/AI memory of GW-7552 and input data area of Profibus master device is
mapped into DO/AO memory of GW-7552, when Modbus type is slave (please
refer section 3.1 Profibus data exchange ).
4.6.1 Input data area
The maximum length of input data is 128 bytes. Before arrange the input
module, the user must arrange and configure the system setting module. The
user can get data and control I/O of Modbus slave device or get DI/DO/AI/AO
of the GW-7552 by read input module.