Instructions

Hardware resources
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PR200 as a master can control up to 16 slaves over one RS485 interface. Each slave can
maintain up to 256 variables. To use the same name and the same address for different
slaves is allowed.
To add an interface, use the context menu of the node Interfaces in the configuration tree
and select Add interface > RS485 (Fig. 4.9). Change the mode to Master in the right
window part.
Fig. 4.9 Master configuration in Master mode
Add the required number of slave devices using the context menu of the new interface (Fig
4.10). Define the name and the Modbus address for each slave.
Following parameters can be set for the slave:
 Name – device name in the configuration tree
 Address – device address in the Modbus network.
 Polling cycle – time between requests (0…65535 ms)
 Retries – number of request retries if no reply (0…255)
 Timeout – maximum time to wait for reply (0…65535 ms)
 Status variable – status of slave device (BOOL variable)
 Start query – start / stop polling (BOOL variable)
 Change register order – reverse the register order according to the method of
storing variables in the device memory
 Change byte order – reverse the byte order in a register according to the method of
storing variables in the device memory
See ALP Help for further details about configuration in Master mode.
To create a variable to be requested click th e icon (Fig. 4.10).
To delete the selected variable click the icon.
The reading request is trigged by the Polling cycle by default. Optionally it can be triggered
by changing a variable of type BOOL.
The writing request is triggered by change of parameter value. Optionally it can be triggered
by changing. a variable of type BOOL.