Could someone please tell me whether the RS232 db9 connector on my SLC5/04 is in fact a null serial cable or does it use a normal (non-null) serial cable?
By the way, I had it wired up with power and when I turn it on, I notice the DH+ green light flash on and off periodically. Does this mean the PLC is defaulting to communicating using DH+? If so how do you force it to communicate using RS232, cause I have a serial port on my PC and don't want to go buy DH+ hardware. TIA
You will need a null modem cable to communicate with the RS232 port.
IIRC, the DH+ port is a separate port (the RJ45 one). Green flashing is the normal state if you don't have anything connected to it.
There is a separate green RS232 LED which will flash when the PLC is receiving RS232 data.
I hope this helps, Cameron:-)
The DH+ is not an RJ45 - just a 2 or 3 wire terminal block IIRC. The LED is probably flashing as it's trying to find other nodes on the network. DH485 (on 5/03 processors and earlier) is RJ45, and you can make yourself look really stupid by trying to use an Ethernet cable on them.
You can communicate with the processor using both DH+ and RS232 at the same time, unless the RS232 channel has been programmed for User mode (data send/receive under ladder program control). If this is the case, you can erase the memory (I think there's a jumper for this, or just leave the backup battery out for a long while), but you'll lose the program and data stored in the processor. The SLCs default to System mode for the RS232 channel, which allows communication using the DF1 protocol.
Regards, Andrew
Uh, yes - sorry about that - I have never had cause to use DH+ in my life and was thinking of the DH485 port on the 5/03.. :-(
I disagree with your 2nd point tho' : IMHO, Ethernet cable is the greatest revolution ever in the long history of DH485 & RS232 comms - no more messing with DB9's and a soldering iron - and is the best way I know to hook a DH485 PV to a 5/03! ..although it does pay to use a different coloured cable to your LAN.
Cameron:-)
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