RSLinx Communication Problem 1

[pfrancine]

We have several Micrologic 1000s and 1500s but only 1 SLC 5/3. When I go to auto config the driver (AB_DF1-1) it keeps telling me "failed to find the baud and parity, check cable and switch settings" I get the same response when I am not connected to the PLC. Does this simply mean the cable is wrong? It is supposed to be a Null Modem RS-232C or a standard RS-232 with a Null Modem adapter (Radio Shack 26-264). I made sure the com port was correct and verified settings with a copy of the program that is in the SLC 5/3 we are trying to communicate with. I must be missing something very simple.

 

[djs]

Try a striaght cable without the null moden adapter. On the A-B website you can find diagrams of the required serial cable.

 

[crthompson]

I've had that problem before... Once I even made my own serial cable via the diagrams...

 

[djs]

In this era of USB ports, most new computers do not have builtin serial ports. USB to RS-232 adapters vary in their compatibility with communications programs that use serial ports. RsLinx is one of the worst. So it might also be your serial adapter. I have had good luck with the Keyspan USA-19HS.

 

[isprog]

re: USB2Serial
You are better off not using USB2Serial. As already mentioned, USB2Serial are problematic depending on whose adapter you have and what software you are using.

Rather get a PCMCIA or an Expresscard serial port adapter card for your laptop. I have never had an issue with industrial programming software (RSlinx, Danfoss MCT10, etc) with either a PCMCIA or Expresscard serial (RS232/422/485) solution.

 

[EddieWillers]

The "Autoconfigure" feature works by rapidly reconfiguring the port for different baud/parity/stop features and sending a two-byte "Echo" command (0x10 0x05). When the controller responds to the Echo command, RSLinx sends a longer command to confirm the BCC/CRC error checking method and determine the Device Type.

Many add-on serial ports cannot keep up with the rapid reconfiguration changes. The best USB/RS232 device I've used is the Keyspan USA-19HS; I've bought a half-dozen of them because I give them away to users who are having this sort of problem.

Remember that Autoconfigure is convenient but not required; if you have the Offline file you can enter the speed/data/parity/error checking/Device Type values directly into the driver.

To run DF1 Full Duplex protocol without handshaking, you only need Pins 2,3 and 5, with pins 2/3 swapped between the PC and the controller. The 1747-CP3 and 1756-CP3 cables from Allen-Bradley are ideal, but any straight serial cable with a null-modem adapter should work.

Another possibility is that your offline file doesn't match the port configuration that is actually running in the controller. SLC controllers can be configured to run ASCII, or DH485, or Modbus, or even to shut down the Channel 0 port.

The last possibility is, of course, that the port has been damaged. They're pretty durable, but I've seen SLC-5/0x ports get damaged by voltage spikes (non-isolated radiomodems are notorious) or just by physical abuse.

 

[jde777]

For the SLC 503 I would delete any previously configured DF1 drivers in rslinx. Then configure the 1747-pic/aic+. It is possible that the port is configured for dh-485 and not df1.
Look at the communication LED that is labelled:
1. Lower End SLC Processors: COMM
2. Higher End SLC Processors: RS232
Unhook your cable-if this LED is slowly flashing, the communication channel is configured for DH485. If the LED is off, it is configured for DF1 communication (full-duplex or half-duplex) or has been disabled.