Allen 1747 CP3 Diagram

PC to SLC-5/4 Communications

Figure 1 Full Duplex Point-To-Point Communications

Point-to-point communication between PC and SLC-5/4 is a DTE to DTE communication link. As shown
in Figure 1 either two DTE to DCE cables with interceding modems may be used or one DTE to DTE (null
modem) cable may be used. The DTE-to-DTE cable is connect to one of the DB-9P connectors on the PC
and to the DB-9P (Channel-0) connector on the SLC as illustrated in Figure 2.

Figure 2 DTE to DTE Connection

To use a DTE-to-DTE cable, you should do the following:

• Configure PC to use DF-1 drivers.

• Use 1747-CP3 or compatible cable with circuit shown Figure 3.

• Set default communication speed to 1200 bps.

• Use Channel-0 (DB-9P) connector on SLC-5/4

• Use Com1, Com2, Com3, or Com4 (DB-9P) on PC

1747-CP3

The 1747-CP3 is a form of a null modem cable. Read the notes on Figure 3 and pay attention to note two.
Note that pin 2 and pin 3 are interchange on the cable and pin 5 is feed straight through. The other line are
only used if hardware handshaking is not or cannot be turn off.

Figure 3 1747-CP3

Baud Rate Selection

To set the baud rate can take up to three steps. The first step is to synchronize the baud rate of the SLC 500
and the PC. If the SLC and PC are already communicating you may skip this step.

Step 1:

• Load RSLinx communication package

• Start application and select communications

• Then select configure driver

• Choose the RS-232 driver DF-1 device

• Click on add new if DF-1 driver is not present

• Select autoconfig and the PC and SLC-5/4 will connect at 1200 bps (default) or the current baud

rate. Then select OK.
The next step is to set the baud rate of the UART in the SLC 500. To perform this operation use the
RSLogix 500 software and follow the steps in STEP 2.

Step 2:

• Load RSLogix 500

• Open an existing project (RSS) file or create a new project file by selecting New under File.

• In the project Tree double click on Channel Configuration under Controller

• Select the Chan-0 System tab

• Select the new baud rate and then apply.

At this point you most likely have lost communication between the SLC 500 and the PC. This is because
the SLC UART is now at the new baud rate and the PC is at the old baud rate. To change the PC’s Baud
rate follow the steps in Step 3.

Step 3

• Start RSLinx application or transfer focus if it is currently running.

• Select communications

• Then select configure driver

• Choose the RS-232 driver DF-1 device if another is highlighted