What do the various RS232 signals mean?

What do the various RS232 signals mean?

The current RS232 signals can be viewed on Tracking :: Devices :: Serial Statistics.  The displayed signals are updated each time the page is reloaded to reflect the current signal activity.  The signals shown are:

 

Acronym

Full Name

Direction

Meaning from the Nodegrid (NG) Port's Perspective

RTS

Ready to Send

From NG

NG is ready to receive data

CTS

Clear to Send

To NG

Target device is ready to receive data

DTR

Data Terminal Ready

From NG

NG is ready to receive data

CD 

Data Carrier Detect

To NG

Target device is ready to receive data

TX Bytes

Transmitted Data

From NG

Cumulative data sent by NG since last reset/reboot

RX Bytes

Received Data

To NG

Cumulative data received by NG since last reset/reboot

 

These signals detected directly correlate to the pinouts of the cabling used to connect two serial devices together.  When correct cabling is used, here is now the pinouts should be aligned:

 

RTS on one side is connected to and detected as CTS by the other side:

  • CTS --- RTS
  • RTS --- CTS

 

DTR on one side is connected to and detected as DCD/CD by the other side:

  • DCD --- DTR
  • DTR --- DCD

 

RX on one side is connected to and detected as TX by the other side:

  • RX -- TX
  • TX -- RX

 

Notes:

  • When the port is Enabled from Managed Devices :: Devices, the DTR signal will always be displayed.
  • When the port is Enabled and Flow Control is set to None from Managed Devices :: Devices, the RTS signal will always be displayed.
  • The RTS and CTS signals are used to regulate data flow when Flow Control is set to Hardware from Managed Devices :: Devices.  This means that if the data rate is exceeded for one side, that side will temporarily stop sending their RTS signal.  While both sides are under the maximum data rate, the RTS and CTS signals are expected to remain active.

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