Cause:

• The timing is incorrectly set.

• There are problems with the modems or the phone lines.

• There is a hardware problem with the host adapter or the concentrator.

Solutions:

• Make sure the timing is set properly.

• Verify the modems and the phone lines.

• If it is possible, swap out the concentrator or switch the positions if there is more than one in the chain (adjust the node number appropriately). If the problem follows the concentrator it is probably a hardware issue with the concentrator. If the problem remains with the position it could be the cable, or a hardware issue with the adapter. If changing the cable does not solve the problem, then run the appropriate diagnostics on the host adapter to determine if there is a hardware problem.