What causes an 'OL9-1600 Not logged in to controller' error in Concept?

Issue
When a connection is attempted using Concept, the above message is returned.

Product line
Concept Programming software

Resolution
This is typically a Modbus timeout error.

• Verify that the transmit and receive buffers are set to High in the PC's COM1: port parameters.
• Try to connect to the PLC in ASCII mode at 2400 baud rate.
• Is the laptop running off a low battery?
• If the PLC is a Momentum, look for a bent pin.
• Are Allen Bradley drivers activated?
• It may be necessary to jumper out the handshaking (DTR/DSR) in the cable. The modified pinouts are included in the attached files.