Advertisement
I.L. 40-201.9
Data communication devices are categorized as either Data Terminal Equipment (DTE) or Data Communication
Equipment (DCE). A DTE is any digital device that transmits and/or receives data and uses communications
equipment for the data transfer. DCE's are connected to a communication line (usually a telephone line) for the
purpose of transferring data from one point to another. In addition to transferring the data, DCE devices are de-
signed to establish, maintain, and terminate the connection. As examples, a computer is a DTE device and a
modem is a DCE device.
By definition the connector of a DCE is always female (usually DB-9S or 25S). Similarly, DTEs are always male
(usually DB-9P or 25P). These definitions apply to the equipment being connected and to the connectors on the
interconnecting cables.
One additional piece of hardware that is required, in some applications, is a "null" modem. Null modem's func-
tion is to connect the transmit line (TXD), pin 2 by RS-232C standard, to the receive line (RXD), pin 3. A null
modem is required when connecting like devices. That is DTE to DTE or DCE to DCE. A DCE to DCE, example,
where a null modem is required, is the connection of a 25 pin, PONI to a modem.
A null modem function can be accomplished in the connecting cable or by separate null modem package. That
is, by using a conventional RS-232C cable plus a null modem. One type of null modem, available from electron-
ics suppliers, is B & B Electronics Type 232MFNM.
1.5.
Setting Change Permission and Relay Password
To gain access to certain communication port functions, the REL 352 must have the remote setting capability
permission SETR set to YES and knowledge of the relay password is required. All communications port func-
tions listed below require SETR set to YES before the actions can be performed:
Update/Change Settings
Enable Local Settings (capability)
Disable Local Settings (capability)
Activate Output Relays (contact testing function)
Access control, both setting permission and password knowledge is required for all communication port options.
Before attempting any of the above functions, the setting of SETR must be verified via the front panel MMI. Us-
ing the setting change procedure in Section 4.5, verify or change SETR such that it is set to YES.
Using comm. port communications, the ability to change settings from the MMI can be disabled.The RCP, Pass-
word Menu Choice "Disable Local Settings" when selected, will block setting changes via the MMI. Blocking the
front panel setting changes, may be useful for situations in which the access to the relay cannot be secured from
tampering by unauthorized persons.
Password:
When the REL 352 is received from the factory or if the user loses the relay password, a new password can be
assigned with the following procedure:
Turn off the relay dc supply voltage for a few seconds,
Restore the dc supply voltage and wait for the relay to complete the self check/start-up routine,
Using RCP, perform the Password Menu choice "Set Relay Password",
Use the word "password" when prompted for the "current relay password" and
Then enter a new password.
Password setting change procedure must be completed within 15 minutes of energizing relay or "pass-
word" will not be accepted as the "current" password.
J-2
Power Automation and Protection Division
REL 352 Version 1.00
Advertisement
