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***slychiu*** · 04-17-2009, 01:57 PM

We have used this circuit before, there seems to be nothing wrong with it
In what way it is not working, do you get any characters displayed on the computer at all?

**dcrera** · 04-20-2009, 04:10 AM

Hi

Comfort reports no response from UCM.

Thanks

 

 

***admin*** · (This post was last modified: 04-20-2009, 04:46 AM by admin.)

I have added comments to the original diagram

Quote:This is a connection cable between the UCM and another 3rd party serial device assuming that that device has a female DB9 connector just like the UCM Hence the UCM is connected to the 3rd party device via a Male to Male DB9 connection. Both UCM and the 3rd party device will Transmit data on pin 2 and Receive Data on Pin 3 (being DCE devices). This is why the pins 2 and 3 on both connectors must be crossed over (2 to 3 and 3 to 2) The monitoring cable which goes to the PC goes to Pin 2 of the FEMALE DB9 connector which plugs into the PC (which has a Male DB9). The PC being a DTE receives data on Pin 2 Hence the switch will connect the PC receive Pin to the transmit side of either the UCM or the 3rd party device

Check the diagram and the pinouts carefully (by reading the pin numbers on the back of the connector) as well as make sure the correct gender of the connectors is used, ie Male to UCM, Male to the 3rd party device and Female to the PC as shown in the diagram and check the cable itself fore short and open circuits
I am sure you will discover the error in the cable or connection

**dcrera** · 04-20-2009, 05:12 AM

Thanks, will feedback.

**dcrera** · (This post was last modified: 05-08-2009, 04:14 AM by dcrera.)

Hi Admin 

I made a serial connection box that can accept comms from either the third party device or from PC to UCM using a 2  x 3 wafer switch using pins 3,2 and 5.

The connection from the third party device communicates with the UCM from both ports if swapped around and switched but the PC to UCM has no comms.

Do I need more wires connected to the PC to UCM ?

Thanks

 

 

 

 

 

 

***ident*** · 05-08-2009, 04:21 AM

The circuit shown in the earlier post was for monitoring the data sent from two devices, a UCM and another serial device using a switch
The switch connects either of the two devices\' transmit pin to the PC Receive pin on Rs232 (ie Pin 2 on the Female DB9)
There is no connection from the PC Transmit pin to the 2 devices
If you need to send data the other way you will need to connect another switch which will connect pin 3 to the selected device, but this must at the same time disconnect the other device. It is easier to just connect individual cables when needed