Download DP5 Programmer`s Guide

DP5 Programmer‟s Guide Rev A4
4.1.19 Request packet: “Autoset Input Offset”
Offset
Value
SYNC1
SYNC2
PID1
PID2
0
0xF5
1
0xFA
2
0xF0
3
5
LEN
MSB
4
0
LEN
LSB
5
0
CHKSUM
MSB
6
0xFD
CHKSUM
LSB
7
0x1C
Purpose: This commands the DP5 to search for an appropriate input offset (i.e. the DC offset of the input
signal as seen by the input ADC.) Generally, the „default‟ input offset should work with most detectors.
(See the INOF ASCII command.) In order for the Autoset Input Offset function to work properly:
1. The input polarity must be set properly (see the AINP ASCII command.)
2. HV & detector temperature (if applicable) must be reasonably stable.
3. An appropriate input offset might not be found if this command is initiated while the input count
rate is high.
Support: This request is supported by the DP5 and PX5, but not the DP5G. (The DP5G does not have a
variable input offset.)
Response: If no errors are detected, the DP5 will respond with ACK OK packet. The DP5 sends the
ACK packet immediately, and does not wait for the Autoset function to complete. The result of this
command is in the status data (offset 36: bit D7) – it returns “Auto Input Offset locked” or “Auto Input
Offset searching”. Status can be polled until the result indicates „locked‟.
Possible errors: If the request packet is malformed or corrupted: CHKSUM, LEN, or PID error ACK
packets can be returned instead of ACK OK.
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