Communications Protocols
6-19
}
for (ch = 0; ch != MAX_CHAR; ch++)
printf("0x%04x\n", crctab[ch]);
}
Manually Disabling ECP for Maintenance
Under certain conditions, communications between the host and Encompass 4 Reader
may be lost temporarily and maintenance may be required. The reader or host is send-
ing out a message and waiting for an
acknowledgment. When the acknowledgment is
not received, the message is sent again. Additional messages are also buffered. Often
the first indication that the Encompass 4 Reader software is in an ECP “loop” is when
the user/technician sees a recurring display of the same message repeated over and
over again on the monitor. The procedure described in the following paragraphs
enables the maintenance technician to change configuration or test tag reading manu-
ally.
Assuming that the ECP timeout is at the
factory default of 12.7 seconds (or other value
that allows enough time for the commands to be manually entered) the following com-
mand sequence may be used to break out of
an ECP loop. This command sequence
uses four ASCII < ` > characters (60 hex) as wild card CRC values.
Note: The ASCII <`> cha
racter (60 hex) is commonly located on the ~ key.
You must acknowledge existing
messages by issuing commands with the generic for-
mat:
#x@‘‘‘‘<eom>
where
# Start-of-mess
age character
x Messa
ge sequence number. This must be the same as the
sequence number of the message being acknowledged
@ ACK (acknowledgment
character)
<‘‘‘‘> Wild card CRC value
for the message
<eom> End-of-mess
age character
The following is a typical sequence after power-on limiting buffered messages.
Note: Ensu
re that no tags are in the field when you are performing this troubleshoot-
ing procedure.
Caution
To avoid damage to the Encompass 4 Reader that us
es an external antenna, ensure
that you have connected the antenna or a dummy load to the reader before applying
To Next Page
Loading...
