The PV is a 2711-k5a2, series H, the comms led is flashing, and the baud rate is set at 19200. the slc is connected to a pc by DH+, a laptop by a 1784-PCM5 cable coming from a RS 403-370 adapter, so is on DH+ as well, and the PV via a 1747-C10 cable into the RS232 port. The laptop and the PV are connected via a SLC500 PIC (1747-PIC)