Panasonic JS-170FR Series Service Manual page 29

Signal on COM3 connector
JP4
1-2 Short
2-3 Short
JP5 JP6
1-2 Short 2-3 Short
2-3 Short 2-3 Short
1-2 Short 1-2 Short
2-3 Short 1-2 Short
Pin8 is CTS (Factory setting)
Pin8 is Ground. CTS is always active.
Pin4 is DCD. DSR is always active. (Factory setting)
Pin4 is DSR. DCD is always inactive.
Pin4 is fixed to +5V. DSR is always active and DCD is inactive.
Pin4 is fixed to +5V. DSR and DCD are always inactive.
1-19
Explanation
Explanation