This trick is for the very special application when we want to communicate with unknown device trough serial communication using our Delta PLC.
If the slave is Delta, we can always use PLC Link.
But what happens when the slave is not delta?
In this case we have 2 options.
First use our DVP12SCM-SL module with 2 extension ports to help us on the frame configuration.
Second the solution we’ll show in this post.
Basically all our PLC have by default 2 communication ports RS485 (below) and RS232 (in front).
And some have a 3rd RS485 port, usable also to send single frames to other slaves.
Once you got the port selected, then you need to set up the port configuration.
Use the below table, or our WPLSoft wizard if you are still WPLSoft users.
On our examples below we used D1036=87H what means:
– Data Lenght 8
– Parity Even
– Stop Bits 1Bit
– Baudrate 9600 bps
Before COM port configuation, we´ll going to use RS instruction.
Basically RS instruction is to configure where I’m going to save the data to be sent and received.
But to trigger the frame, you will need to trigger special mark.
Once this mark is high, the PLC send the frame configurated in the RS instruction.
If on the other way around, our PLC is waiting for some transmision, then we´ll need to wait until the data is recieved.
The mark that will tell us when the data is available is:
And you will find the info on D1070 – D1085 special registers range.
To help you on this special application, download the following Send Frame trough RS232 and Send Frame trough RS485.
We also add some section of the manual with the special marks to be aware when you play with this instruction.
When you work with comunications, is always advised to have some sniffer, to see what happens on the network. In RS485 case, I recommend to have IFD6500 and any freeware Modbus sniffer.
And remeber, with comunications…always patience.