Modem to Modem help needed

Winchester

Diamond Member
Jan 21, 2003
4,965
0
76
I need some help figuring out why this configuration is not working. We can get the modems to complete the handshake/negotiation etc but I can not get any data across. Further information is in the layout below.

We need to get a terminal up to the PLC device from practically anywhere. Both modems are identical.

Layout
 

VirtualLarry

No Lifer
Aug 25, 2001
56,587
10,227
126
It sounds to me like there is a configuration problem on the PLC modem side. Some sort of RTS/CTS/DSR/etc. issues with the serial cable signal from the modem, that isn't an issue when connected directly via serial cable.
 

Megatomic

Lifer
Nov 9, 2000
20,127
6
81
What PLC are you connecting to? We connect our WonderWare HMI system to a remote AB PLC5 at our water intake station (20 miles away) via 56K modem over Sprint phoneline, but to be honest it is our least reliable system and we have to reset communications at least once a month.