Spontaneous data communication and general query

The sample program presented here shows an IEC 60870-5-104 master with Low Level interface and a simple communication of two data points. One data point is transferred spontaneously in control direction, the other in monitor direction. In addition, a general interrogation is configured for the data point in monitor direction.

Download TwinCAT XAE Project (*.zip): IEC870_104_LowLevel_Master_easy.zip

In the sample, the following parameters are set for the central station (master):

Server Host address (IP address of the slave): 127.0.0.1 (At least this parameter must be adjusted individually)
Server port address (port address of the slave): 2404
k: 12
w: 8
t0: 30 s
t1: 15 s
t2: 10 s
t3: 20 s
General ASDU address: 3
Cause of transfer size: 2 octets
Common ASDU address size: 2 octets
Information object address size: 3 octets
Max. APDU length: 253

	We make no claim to completeness and correctness. Set the IP address of the slave, both in the master part and in the slave part! Verify that port 2404 is not blocked by a firewall! The connection is established after the start of the program. The data points are managed in the Global Variable List (GVL).