How to set up HEART Communication with the PLC by using Solidot EhterNet/IP Slice I/O

Left: Solidot Technology EtherNet/IP slice I/O couplerXB6S-EI2002

Middle: Solidot Technology EtherNet/IP integrated (vertical) I/OEI4-0016A

Right: Solidot Technology EtherNet/IP integrated (horizontal) I/OEI3-3200

In the field of industrial automation, PLC combined with remote I/O has been increasingly widely used. In order to ensure the stability and reliability of communication, the heartbeat mechanism is usually used, which plays an important role in monitoring the connection status during the communication process.

1. Heartbeat Mechanism Principle

The heartbeat mechanism monitors the communication status by periodically sending variable data or high and low level signals. Here, a concept called heartbeat address is involved. The heartbeat address is a variable. Generally, we use Boolean type or integer type.

2. Implementation Method

1. Monitor the EtherNet/IP coupler status word

At present, the only EtherNet/IP protocol products of Solidot Technology that have the coupler status word function are the slice type. Take XB6S-EI2002 as an example.

The coupler has two status words that occupy the first two word addresses of the input data. When the communication is in normal state, the status words are 0 and 0 respectively. 

If you only monitor the status word to be 0 and 0 to judge the normal communication status, it is unreliable, because after disconnection/freeze, the status word data is not refreshed and still remains 0 and 0. 

Therefore, we can write other values to the two status word addresses at a time of 1S in the program, such as writing 5 and 5 respectively. When CR2006 is OFF, the status word is 0 and 0. When CR2006 is ON, the status word is overwritten with 5 and 5. When CR2006 is OFF again, the status word is automatically refreshed to 0 and 0, and the cycle repeats. When the monitoring status word is not 0 and 0 and the time exceeds 1S, it can be determined that the slave is offline or the coupler has a general fault as shown in the figure below:

When CR2006 is OFF, the status words are 0 and 0:

When CR2006 is ON, the status words are 5 and 5:

2. Periodic DO triggers DI signal jump. Since the EI3 and EI4 series of EtherNet/IP protocol integrated products of Solidot Technology do not have the status word function, the DI signal jump can only be triggered by periodic DO. When the PLC monitors the DI signal for a long time without change, it can be determined that the slave is offline.

The above is a detailed introduction to the implementation of the heartbeat mechanism of PLC and I/O communication of EtherNet/IP protocol of Solidot Technology. If you have any questions, please feel free to ask us, we will serve you wholeheartedly!