MAX232 and RS232

[spilleravr]

Hello,

 

I want to send 8 bytes of data from a microcontroller to the PLC and display it. I am using a V1040 with a V200-18-E5B snap-in module.

I am using MAX232DW IC to convert UART to RS232 from the MCU. 

At the moment the MCU is sending the following bytes 1 time per second: 0x23 0x05 0x50 0x05 0x50 0x05 0x50 0x05 0x50 0x2B 

The first byte 0x23 is the start byte and the last byte 0x2B is the end message byte.

 

Do I have to include the start and end byte in the message length?

 

And do I need to do something with the DTR and DSR signals of the RS232 connector? At the moment I am using a 2 meter long 4 pin RJ11 cable, where pins are in the following order - GND, RxD, TxD, GND. So I am sending from the MCU to the PLC's RxD pin and from the PLC to the MCU from the PLC's TxD pin (Sending not implemented yet). The cable is a straight cable. The DIP switches which choose between RS232 and RS485 are set for RS232. 

 

I watched the seminar about the FB protocol and made the ladder exactly like that, minus the message. 

 

I am expecting to recieved the message above.

 

I have included the project file aswell.

 

The plc does not recieve any messages I am sending. I check with the online "glasses" and the Session byte stays 0 all the time.

 

Does anyone have any idea what could I be doing wrong?

 

Thanks in advance!

 

T

COM2_test.vlp

[spilleravr]

An update:

 

The PLC recieved only the 0x23 aka '#', which is supposed to be the start of the text byte.

 

Numbers of bytes recieved stays at 0.

 

Did I understood correctly that the PLC converts the recieved ASCII into a DECIMAL value?

So If I send a 0x05 then it converts to it to ENQ (enquiry) ?

 

Update during writing of this post:

 

I sent 0x23 0x05 0x50 0x05 0x50 0x05 0x50 0x05 0x50 0x2B and the PLC displayed "*P*P*P*PP". Changed SCAN protocol variable to Stream with a vector length of 5 and convert 2 bytes to one linked element.

 

EDIT: FB protocol was all about sending ASCII - I can do that now.