Beijers E1000 - Modicon Modbus Master

I am trying to set up a E1101 to be a Modbus master to a Deep Sea Electronics 5220 controller. The DSE5220 has a RS485 connection.

At the moment I am using a Modbus Slave Simulator to simulate the DSE5220 (download from http://www.modbustools.com/ )but are finding that I get a lot of "1:Comm err stn 10" messages on the E1101 even though the data is being updated across the Modbus connection.

There is no handshaking and the Baud Rate is 9600, 8,n,1 so pretty standard.

Other than the RTU Silent Time under the General settings tab in the driver I can't see too much to adjust to help with data collisions.

I have been sniffing the communication with LookRS232 and the data is below. Where a line status error ocurs the comms. locks which seems to be causing the error on the screen... anyone got any ideas ???

0572.438<0A 03 02 00 4E 9D B1
0572.344<0A 03 00 00 00 01 85 71
0569.953<0A 03 02 00 4E 9D B1
0569.875<0A 03 00 00 00 01 85 71
0569.391<0A 03 02 00 4E 9D B1
0568.969<0A 03 00 00 00 01 85 71
0567.094<01 00 01 85 71
0567.063|A line-status error occurred
0566.563<0A 03 02 00 4E 9D B1
0566.438<0A 03 00 00 00 01 85 71
0564.000<0A 83 03 70 F3
0563.953<0A 03 02 00 4E 9D B1
0563.657<0A 03 00 00 00 01 85 71
0563.157<0A 03 02 00 4E 9D B1
0563.078<0A 03 00 00 00 01 85 71
0562.578<0A 03 02 00 4E 9D B1
0562.500<0A 03 00 00 00 01 85 71
0561.985<0A 03 02 00 4E 9D B1
0561.922<0A 03 00 00 00 01 85 71
0559.969<80 00 01 85 71
0559.953|A line-status error occurred
0559.453<0A 03 02 00 4E 9D B1
0559.391<0A 03 00 00 00 01 85 71
0552.985<20 00 00 01 85 71
0552.969|A line-status error occurred
0552.485<0A 03 02 00 4E 9D B1


NOTE:
0A 03 00 00 00 01 85 71 is the string from the Master
0A 03 02 00 4E 9D B1 is the reply from the Slave

I believe the problem was being caused by having two controllers connected, one to each comm port. As one driver wasn't connected to a device when it faulted it stopped the comms of the other driver !!! this is what was causing the line status error.