Publication 5390-001 Revision B
24
Harvard Apparatus Model 33 Twin Syringe Pump User's Manual
Appendix D: RS-232 Specifications
Pump Chain
Pump Port 1: Computer
control side
Pump Port 2: Connection for
remainder of
pump chain
Baud Rate: 300, 1200, 2400
or 9600
Word Size: 8
Parity: none
Stop Bits: 2
TTL Connections are via a 9 pin D-sub type connector.All inputs are internally pulled
up to a logic high. All user definable pins are controlled via the IN and OUT pump
chain commands. See Pump Chain Commands.
Pin Assignments
1. Vss (Ground reference,
logic low)
2. Directional Indicator:
Low – Syring 1 Infusing
High – Syringe 1 Refilling
3. Pump Running Indicator
Low - Pumped Stopped
High - Pump Running
4. User Definable Output
5. User Definable Output
6. Foot Switch Input
Falling edge starts/stops pump
7. Timer Input
Rising edge starts pump
Falling edge stops pump
8. Directional control input
Rising edge sets Syringe 1 to infuse
Falling edge sets Syringe 1 to refill
9. Vcc (Logic High Reference)
Figure 10.TTL Connector Specifications
Figure 9. RS-232 Specifications
Appendix E: TTL Connector Specs
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