Modicon Modbus communication problem

[Golden_H]

I am using LabVIEW 8.2 to communicate with modicon PLC via SCP111 rs232 PCMCIA card. When I send a command such as 01 06 00 01 00 01 plus CRC, there is no response from PLC.

I have configured PLC and SCP111 in PL7.  Is there anyone had implemented this communication? Can you give me some suggestions?

帖子被Golden_H在12-06-2007 11:22 PM时编辑过了

[K C]

Hi,

Does the PLC supports the ModBus loopback command ? Maybe you can try this.

[unclebump]

Download portmon so you can watch both sides of the communication.

http://www.microsoft.com/technet/sysinternals/utilities/portmon.mspx

[Golden_H]

thank you for your replies. I have solved this problem. My engineer has buyed wrong cable( CD 1030), so I make a CC1030 then jumper 4,5 pins together, 6,8&20 pins togeter too, It is Ok now.

[falkpl]

It is always a good idea to check the baud rate and communication settings and wiring then use a simple vi or hyperterminal and send a example string (see the manual for a device specific string) to validate communications over modbus.