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 enabled?
- It may be necessary to jumper out the handshaking (DTR/DSR) in the cable. The modified pinouts are included in the attached files.
Legacy KB System (APS) Data: RESL198297 V2.0, Originally authored by DaSo on 04/17/2009, Last Edited by DaSo on 02/27/2013
Related ranges: Concept