TTL Ports – Button Pumps
NOTE: This page applies to the pumps listed in my compatibility page.
All pumps OEM and others, the TTL output ports are available on the DB9 connector on the rear panel. This connector is not the RS-232 port!
The following chart shows the pin input and output assignment.
The input voltages must be within the following ranges to guarantee recognition of logic levels, voltages:
- TTL logic low (0): 0 to 1.5 V
- logic high (1): 3.5 to 5.25 V
TTL Ports – OEM Pumps
OEM pump models are configured for installing in equipment of your design. The pump control circuit board is set up to take soldered connections rather than a single plug.
This diagram from the OEM Pump Manual shows the solder pad location and the location of current limiting resistors.
Accessing TTL Ports Via RS232
Logic levels of pins 2, 3, 4, and 6 can be queried from an attached computer using the RS-232 ‘IN’ command.
The output logic level of pin 5 can be set with the RS-232 ‘OUT’ command.
There’s more details in your pump manual.
Power on Pin State
Pumps do not remember the state of the TTL outputs after power cycling. All the pins come on high at switch on regardless of previous state.
Users of the Valve Control Box
If you’re a user of the Valve Control Box inverting the signal is just a matter of changing the valve activate switch from Infuse to Withdraw.