Does anyone know why a number of pins on the M1XSP cable are soldered together?

[CORT]

Does anyone know why a number of pins on the M1XSP cable (at the DB9 connector) are soldered together? This is the cable that comes with the M1XSP. It looks like several pins are shorted together. The manual does say why. Thanks

 

[dutchyn]

A educated guess:

http://www.nullmodem.com/NullModem.htm

Can you tell us which wires are connected together?

Chris D.

 

[CORT]

A educated guess:

http://www.nullmodem.com/NullModem.htm

Can you tell us which wires are connected together?

Chris D.

Pin 1 is jumpered to pin 4 and soldered to pin 6
Pin 7 is soldered to pin 8

 

[WayneW]

IIRC, that cable is for use with the HAI thermostats. Maybe the thermostats are demanding voltages or signals on those pins.

 

[dutchyn]

The discussion on null-modems explains it: there is no modem. Therefore there is no carrier detection between the two endpoints; and they're always ready (powered up); so connect pins 1(CD), 4 (DTR), 6 (DSR) together. The two endpoints are [relatively speaking] high speed devices, so there's no buffer overflow and so whenever the line is clear to send (7=CTS), the other end is ready (8=DTS). So, connect these as well.

This is all a throwback to the days of 300/1200/2400 baud modems that operated over POTS.

 

[CORT]

The discussion on null-modems explains it: there is no modem. Therefore there is no carrier detection between the two endpoints; and they're always ready (powered up); so connect pins 1(CD), 4 (DTR), 6 (DSR) together. The two endpoints are [relatively speaking] high speed devices, so there's no buffer overflow and so whenever the line is clear to send (7=CTS), the other end is ready (8=DTS). So, connect these as well.

This is all a throwback to the days of 300/1200/2400 baud modems that operated over POTS.

You sound like you know what you are talking about. I am a little confused as to how I am to make the cable to connect an AnyNet to the M1XSP The diagram for the Uplink Anynet cable shows only 3 connections: ground to ground, TD to RD and RD to TD. The diagram makes no note of connecting DTR, DSR, CTS, or DTS. Are these connections inconsequential for this application? Should I strictly make my cable according to the Elk diagram--that is none of the extra connections? Thanks.

 

[WayneW]

You sound like you know what you are talking about. I am a little confused as to how I am to make the cable to connect an AnyNet to the M1XSP The diagram for the Uplink Anynet cable shows only 3 connections: ground to ground, TD to RD and RD to TD. The diagram makes no note of connecting DTR, DSR, CTS, or DTS. Are these connections inconsequential for this application? Should I strictly make my cable according to the Elk diagram--that is none of the extra connections? Thanks.

The AnyNet doesn't require the extra (forced) signals that the HAI thermostat does. You are good to go with 3 wires.