Crystal XP2 User Manual

PN: 2975 Rev F, 3/2004
Page 14 of 24
PRESSURE is Our BUSINESS
™
Troubleshooting the Digital Interface
The following section gives possible reasons for various error codes.
N,Ø The “Ø” indicates there were no overrun or framing errors, so the command
was properly received. However, the “N” means the XP2 could not match it to
any allowed command. This means the syntax must have been wrong. The
command is rejected and nothing is done.
Possible reasons:
Instruction sent without a comma between “P” and “U” of the “?P,U” query.
More than 30 seconds passed to finish a command.
Line termination is incorrect; send carriage returns (CR) only, do not send line
feeds (LF).
N,2 XP2 buffer overflow, no action. In an overrun, bytes are lost, consequently the
XP2 will not be able to match the command string. If it can’t find a match, it
returns “N”.
Possible reasons:
Not enough time allowed between commands. This error should not occur if
the communication flow control is set to hardware. Check the communication
parameters. If hardware flow control is not available, wait 50 milliseconds
between receiving a complete response to a command and sending the next
command.
N,4 Framing error: Bytes were lost. Therefore, the command could not be matched.
A framing error can sometimes occur after power-on, after reset, or when the
batteries are changed; see the Programming Tips section for suggestions on
handling this.
Possible reasons:
Noise on the line either created a false start bit or obscured the stop bit.
Multiple, but infrequent, framing errors are probably due to noise on the
connection.
Frequent framing errors more likely mean the XP2 or the PC is not operating at
precisely 9600 Baud.
Occasionally, plugging the RS-232 connection into the XP2 will create a single
framing error.
N,6 Both buffer overrun (N,2) and framing errors (N,2) occurred during this
command. The “6” represents the binary OR masking of the two bits used to
indicate a buffer overrun (bit 1) and a framing error (bit 2).
Possible reasons:
Look at “Possible reasons” for troubleshooting the N,2 and N,4 error codes,
above.

Crystal XP2 Specifications

General

Accuracy	±0.25% FS
Display	LCD
Pressure media	Non-corrosive gases
Operating temperature	32°F to 122°F (0°C to 50°C)
Measurement Range	0 to 15 psi
Operating Humidity	90% RH (non-condensing)