Disable DCD in RS232 (beginner)

moty66

Hello, is there any way in netlinx programming to tell the processor (NI-700) to disable the pin1 (DCD: Data Carrier Detect) even if it is connected ?

If I cut the cable manually, my NI-700 reads everything from RS232 but if it is connected I can't
The contrary works on my PC, if the DCD is connected I can control the device with it's software from the PC, but if it is disconnected the device software gives me error

Any help ?

Thanks

regallion

Download AMX-PI if you don't already have it and check out all the commands available for the NI-700 there.

Alternatively you could look to shorting out various pins on the serial cable to fool the controller. I've done this with CTS / RTS before but must confess I've never had an issue with the DCD pin. There's a diagram for creating a loop back tester here: http://www.lammertbies.nl/comm/cable/RS-232.html

What's the device you're trying to control?

moty66

Thanks for the reply, I have the manual for the Ni-700, but I couldn't find anything about the DCD

I am controlling a keypad of a local company, the used a protocol very smiler to BatiBus
the device converts BatiBus to Rs232

here are the settings that I use in my PC

BaudRate 4800
DataBits 8
DiscardNull False
DtrEnable True
Handshake None
Parity Odd
RtsEnable True
StopBits One

In the manual of the device say the I can to short the DCD with RI saying that the DCD is always true and the RI always false ! The manual is in italian so I can't paste it here

DHawthorne

The AMX serial port isn't quite standard because it supports 232, 422 and 485. There is no DCD connection. What you are seeing on pin 1 is the RX line on the 422/485. That's why it's not recommended to use a molded cable with all the pins connected. Most devices you only want pins 2,3 and 5, and if there is flow control add 7 and 8. The rest should not have anything on them, or it may result in some unexpected behavior. In other words, clip that connection on pin 1. If you have to jump any lines together to make the device work, do it on the device side and don't run it to the AMX end of the wire.

moty66

DHawthorne wrote: »

The AMX serial port isn't quite standard because it supports 232, 422 and 485. There is no DCD connection. What you are seeing on pin 1 is the RX line on the 422/485. That's why it's not recommended to use a molded cable with all the pins connected. Most devices you only want pins 2,3 and 5, and if there is flow control add 7 and 8. The rest should not have anything on them, or it may result in some unexpected behavior. In other words, clip that connection on pin 1. If you have to jump any lines together to make the device work, do it on the device side and don't run it to the AMX end of the wire.

Thank you, I'll follow this advice

Regards
M.