Watson-Marlow 504U/RL - Manual (Page 5)

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Set the Auto/Man/Max switch to Auto.
For all auto and remote control operations, the drive is supplied with a 6 pin waterproof connector (UP 0055).
Correct assembly of the 6 pin plug is essential or the ingress protection standard will be
compromised. Never apply mains voltage across any pins on the 6 pin socket. Up to 30V
may be applied across pins 2 and 3, but not across other pins because permanent damage,
not covered by warranty may result.
The pump is controllable by an analogue process signal of up to 30V or 32mA. The pump will provide an increasing
flow rate for rising control signals (non-inverted response) or an increasing flow rate for falling control signal
(inverted response).
• Signal offset is the process signal level which has to be reached in order for the pump rotor to start rotating.
• Signal range is the change in process signal level necessary to produce the required change in pump rotor
speed.
For example, when using a 4mA to 20mA process signal:
Pump Response Signal Offset Signal range
Non-Inverted 4mA 16mA
Inverted 20mA 16mA
For voltage modes a stable variable DC voltage source can be used in conjunction with a DC voltmeter, (maximum
30V DC) or a remote potentiometer. Polarity set for non-inverted response. Reverse polarity for inverted response.
Voltage signal
Input impedance 220 kohm
Response Range V Offset V Pin 2 Pin 3
Non-inverted 5 to 30 0 to 30 – +
inverted 5 to 30 0 to 30 + –
For current modes the same DC source can be used in conjunction with a DC milliampere meter. Polarity set for
non-inverted response. Reverse polarity for inverted response.
Current signal
Input impedance 250 ohm