2 - Hardware Setup
Communication Interfaces
Cavro® XLP 6000 Modular Syringe Pump Operating Manual, 734237-C, en
2 - 5
Examples of cabling connections are shown in Figure 2-2, Figure 2-3, and
Figure 2-4 on the following pages.
2.3.1
RS-232/RS-485 Interface
The RS-232 interface automatically converts the protocol to RS-485 for the
benefit of any other devices which may be connected to the XLP 6000’s RS-485
communication bus (this constitutes the so-called “multi-drop” device
configuration).
Note: The RS-232 interface does not support hardware handshaking and
requires only three lines: RXD, TXD, and Signal Ground.
When using a multi-drop arrangement, up to 15 pumps can be addressed by the
controller on the same communications bus. Take special care to ensure that the
RS-485 A and B lines are not reversed. Refer to the cabling illustrations on the
following pages. These illustrations show the multi-pump cabling for RS-232, RS-
485, and CAN connections, respectively. Also shown is the external termination
scheme for the RS-485 chain.
2.3.2
CAN Interface
The CAN interface is a two-wire serial system. The bus is driven differentially in a
manner similar to RS-485. The major difference is in the protocol. The CAN
protocol is designed to allow any device on the bus to send a message at any
time. This is unlike other two-wire interfaces in which the slave devices can only
transmit in response to a query. Using the CAN interface, the pump can send a
message to inform the master that it has completed its task. Anti-collision
detection (which reconciles problems that occur when two devices talk at once) is
carried out by the CAN controller hardware.
Caution! Always power off pumps before connecting to or disconnecting from the
bus.
