Can I use my PB-24 or PB-24SM with a KPCI card from Keithley?
Yes, but there are some important differences from use of the PB backplanes with the PIO-SSR-xx ISA boards. These differences fall into three categories: cabling, channel assignments and logic levels.
Cabling: The CAB-SSR ribbon cable is the only cable Keithley stocks which provides a card edge connector required by the PB-24 or PB-24SM backplanes. The other end of this cable is a 50-pin header.
The connectors of the KPCI-PIO96 can receive this 50-pin header directly. Up to four PB backplanes can be controlled with a single KPCI-PIO96.
Other KPCI cards such as the KPCI-PIO24, KPCI-3160, KPCI-3108 or KPCI-3130 can also interface to this CAB-SSR cable, but cable adapters are required such as the ADP-5037 or STA-3108-D1. See the configuration diagrams on the KPCI product data sheets for more information.
Channel Assignments: Even though the digital I/O of the KPCI cards terminates in a 50-pin header (directly or with cable adapter), the channel assignments are different than with the PIO-SSR-xx series. The software needs to take these channel assignment differences into account.
Relay # Port of PIO-SSR-xx Port of KPCI-PIO96 0-7 A B 8-15 B C 16-23 C A
Logic Levels: Relative to operation with PIO-SSR-xx boards, the logic is reversed when using a KPCI-PIO96 or other KPCI board:
- a logic 1 will put the relay into an OFF state
- a logic 0 will put the relay into an ON state
- a value of 1 means the input is OFF
- a value of 0 means the input is ON
The ports of the KPCI-PIO96 will be high impedance inputs at PC power up or reset. Output relays will be OFF when connected to these inputs. To control output relays, the ports of the KPCI-PIO96 must be configured for output.
As soon as the channels are configured for output, they will also be at a default value of 0, so output relays will come ON. Write a 1 to the bit (0xFF to set all bits in the port to a 1) to turn the relay back off. This channel configuration process can be accomplished in the DriverLINX Configuration Panel; the configuration for output and setting all lines to a logic 1 can take place at driver loading during the boot process.
Your application must be able to tolerate this momentary glitch from configuring the channel for output and setting the lines to a logic 1 state. Otherwise, use of the SSIO-24 with the SM-xxxx modules is recommended when using a KPCI board with solid state relays to control external equipment. The SSIO-24 has a protected mode of operation which allows greater control over startup sequence.
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