2.5 Communication Timeout
To ensure that RS-232 packets do not compromise the operation of the LCD display, the Ultimus V dispenser has
a Communication Timeout safeguard. As soon as the dispenser receives an Enquiry (
ENQ
/
0x05
) from the client, it
responds with an acknowledgment (
ACK
/
0x06
). The dispenser enters a communication-hold state and awaits the
next text packet(s). If no text packet is received within 2 seconds, the dispenser sends a Failure Command (
A2
) text
packet to the client and removes the communication hold. Any characters received by the dispenser will reset the
timeout. When a failure occurs, the client must restart the communication sequence by (1) sending an End of Text
(
EOT
/
0x04
) and then (2) starting a new Write or Read sequence by sending an Enquiry (
ENQ
/
0x05
).
2.6 RS‑232 Commands
This section contains the RS-232 commands for the Ultimus V dispenser. Each sub-section includes a brief
description of the command, the command format with the text packet data attached to the command, and, if
necessary, the format of the return command along with its attached data.
These commands are contained in the Command part of the text packet, shown below:
[STX] [No. Bytes] [Command] [Data] [Checksum] [ETX]
NOTE:
A hyphen (
-
) represents an ASCII space value (hex
0x20
).
2.6.1 Response Commands
These commands are used to communicate command success or failure between the client and the dispenser.
2.6.1.1 Success Command (A0)
This command is sent when a command is successfully executed.
Text packet structure:
(STX) + 02 + A0 + 2D + (ETX)
The above text packet in hexadecimal format:
STX
0
2
A
0
2
D
ETX
0x02
0x30
0x32
0x41
0x30
0x32
0x44
0x03
2.6.1.2 Failure Command (A2)
This command is sent if a command fails to execute. This can be caused by an error in the text packet or if the
transmission was interrupted and timed out (if the client takes more than 2 seconds to send a text packet),
Text packet structure:
(STX) + 02 + A2 + 2B + (ETX)
The above text packet in hexadecimal format:
STX
0
2
A
2
2
B
ETX
0x02
0x30
0x32
0x41
0x32
0x32
0x42
0x03
Appendix B — RS‑232 Protocol (continued)
Ultimus V High Precision Fluid Dispenser
50
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