koyo direct 205

[Guest Guest_larry]

Hi everyone, I write a program to talk to the Direct205 PLC via Modbus, the program works fine except for certain PLC slave addresses. For example I set the PLC address to 0x0A(10) on the secondary port and send the following command to the PLC(writing 506 to holding register at 401051): 0A 06 04 1a 01 fa ab 51 I get the response : 0A 86 01 F2 62 It seems that I can't write( to this address with number 256-511), If I change the number below 256 or higher than 511, then it works fine, it also works if I change the PLC id to 0x0b(11). At first I thought maybe the CRC were wrong, but if that's the case I wouldn't get any response at all. Anyway I just couldn't figure out what went wrong, if you could give me some help, it will be great. Thanks, Larry

[Guest unreg]

Just an off the wall observation here. In the range mentioned, 256-511, bit 8 (binary value 256) is on. Outside this range the bit is off. Maybe this has an effect on type of register you're sending to or the comm. format.

[Guest Guest_guest]

Hi, Thanks for the suggestion. I am quite new to set up the DL205 PLC, is there a command or trick to set the PLC back to the factory default? I just want to see whether this problem is related to the specific settings I have or something else. Can someone else who have DL205 PLC give it a try and let me know the result? Thx, Larry