1747-pic

[jimcav]

good afternoon all

I had to pull out the old 1747-pic module my question it has a 25 pin connection I need to go to a 9 pin connection do pin 2 and 3 get crossed as a null modem or is this a straight connection 2 to 2 and 3 to 3 ?

 

[drbitboy]

https://literature.rockwellautomation.com/idc/groups/literature/documents/in/1747-in024_-en-p.pdf


?

 

[Corsair]

Voltage Maker/Taker

I always use a voltmeter to figure this out as it depends on what you are wiring to, etc.

As I remember it for a 25 pin - 7 is the signal common. Hook a meter from it to pin 2. It may have a low voltage or it may be negative as much as 12 volts. If it has the higher negative voltage it is the 'maker' (transmit). Otherwise it is a voltage 'taker' (receive). Hook the meter from 7 to 3 and see it it makes or takes voltage. Do the same thing for the device on the other end.

When you construct the cable you must hook 'maker to taker', never 'maker to maker' or 'taker to taker'.

Handshake jumpering is another issue. Typically pin 4 jumped to 5 on the 25-pin end. More jumpers may be needed.

I think 5 is the common on the 9-pin end.

 

[joseph_e2]

What PLC are you connecting to?



Do you have an old laptop running Windows XP SP2 or older with a native COM port? If not...probably don't bother. SP3 broke the RS232 driver and virtual COM ports don't work with the PIC. As an alternative, look at this:
https://www.plccable.com/allen-bradley-1747-uic-usb-to-dh485/




As for the 25pin question, I made a cable to connect a PLC5 DB25M to an HMI. On the PLC5, pin 2 is Tx, pin 3 is Rx, pin 7 is Gnd. On the PC, pin 2 is Rx, pin 3 is Tx, and pin 5 is Gnd. We used a DE9F to DB25M adapter that connected:
25 Pin 9 Pin
Pin 2 Pin 3
Pin 3 Pin 2
Pin 7 Pin 5
This makes the adapter a null modem connector.


I don't know if that's how your adapter is wired, but the "standard" (there really isn't one...) is for pin 7 to be the signal common on the 25 pin side while pin 5 is common on the 9 pin side.

 

[jimcav]

25 pin to 9 pin

I am using an old windows NT laptop to upgrade the firm ware on a panel view 550 2711-ka5a. on the 1747-pic there is a 25 pin female i need to connect it to a 9 pin male com1 on the computer. The 25 pin to 9 pin adapter in a null modem where 2 and 3 are crossed. The panel view firmware update tool will not connect, it tell me to cycle power on the panel view. I am providing power to the dh485, because the 550 is connected to a 502 processor. I am not sure about the adapter.

Thanks

 

[Ken Roach]

The 25 pin to 9 pin adapter in a null modem where 2 and 3 are crossed.

The RX and TX assignments are opposite on DB25 and DB9 connectors, so a "2-3 swap" is actually "straight-through".

The 1747-PIC installation instructions suggest you also need the DTR and RTS pins connected as well (to DSR and CTS on the 9-pin side, respectively).

Having the PanelView DH485 daughtercard powered by the connection to the SLC-5/02 is good and correct. With two devices on the network, the DH485 token should be passing (even without the PIC active) and the network LEDs should be steady instead of blinking.

 

[jimcav]

thanks Ken

So here is the crazy part the program for updating the firm ware on the panel view 550 requires that rslinx is not running and has no control over com port.
I am going to load rslinx on the old laptop and see if rslinx can see the 550 and the 502 on the dh485 through the 1747-pic. Any other ideas?

Thanks for all the help