M-2911 BlueJay Wireless Data Transceiver
–8–
Intercharacter Time-out:
ATT=nnC, ATT=nnn ms
1 to 50 Character Times, or 1 to 199 milliseconds
This parameter sets the time that the M-2911 will wait after receiving characters to send a packet. If data
bytes are coming in as a constant stream, the M-2911 will transmit a data packet each time the number of
bytes specified by the ATN parameter is received. If there is a pause in the data (such as at the end of an IED
packet), the M-2911 will transmit the bytes received after the ATT delay. As with the RS-422/485 transmit
gating parameters, this can be specified in Character Times or milliseconds. The default value is 3 Character
Times, or 3mS at 9600 bps. A low setting is desirable since it allows data to be sent as soon as possible, but
at times, a high setting is necessary to permit data to be collected into reasonably sized packets to allow for
better efficiency.
Maximum Packet Size:
ATN=nn
1 to 64 Characters
The M-2911 sends data in packets of multiple bytes, and will transmit the data packet after a specified
number of bytes is received (or if there is a delay greater than the ATT Timeout described above). The
number of bytes can be specified between 1 and 64 Characters, with a default value of 64. In general the
largest size is desirable, but in some cases (for example a protocol with fixed number of bytes in each
transfer) a setting to match the IED characteristics may be better.
View Settings:
ATV
This command will display the model name, software version, serial number, and basic settings of the unit.
Exit and Save:
ATZ
▲
CAUTION:
This command
MUST
be sent to the unit after any changes are made to save and exit from
command mode, otherwise all information will be lost.
Typical Connections Guide
The M-2911 can be applied in one of two methods. An example of each connection configuration utilizing a
Beckwith Electric M-2001B as the target IED is given below:
1.
Point-to-Point Configuration:
In the Point to Point configuration, two M-2911s are configured to
communicate only to each other. One is connected to a PC, modem, etc. and the other is
connected to an IED.
Detailed elements of a typical Point-to-Point configuration are as follows:
a. One M-2911 is connected to a PC COM port using a straight-through RS-232 cable.
b. The second M-2911 is connected to the RS-232 port of a M-2001B Tapchanger Control
using an RS-232 straight through cable and gender changer.
Communications can now be established between the PC and M-2001B as if they were directly
connected using a RS-232 cable. In this example, if the M-2001B TapTalk Communications
Software were to be used, the user would select the COM Port the M-2911 is connected to on the
PC side, and then connect normally to the M-2001B.
2.
Point-to-Multipoint configuration (also known as Master/Slave):
In the Point-to-Multipoint
configuration, one M-2911 is configured as the Master unit with multiple-connected IED units
configured as Slaves (see AT Commands, Addressing section for Master/Slave setup). This
configuration may be used where, for example, the Master unit is located in a control house and
the slaves are spread out throughout a substation yard.
