Allen-Bradley 1771-ASB Remote I/O Adapter Module
The Allen-Bradley 1771-ASB Remote I/O Adapter Module physically resides in a Universal I/O Chassis, and acts as a slave in an Allen Bradley subnet in an EPICS control system. The 1771-ASB Remote I/O Adapters are linked via subnet connection to other Remote I/O Adapters in Allen Bradley 1771 Series I/O Chassis, Allen-Bradley RediPANEL Pushbutton Modules, and back to a VMEbus I/O scanner. They correspond to the ADAPTER number when configuring an Allen-Bradley subnet. An Allen-Bradley / EPICS subnet allows for up to 8 adapters to be located on one Allen-Bradley subnet link.
1771-ASB Remote I/O Adapter Module Configuration
Refer to figure 4.1 for the following instructions. There are three steps involved in the configuration of a 1771-ASB Remote I/O Adapter Module, the first involves the setting of the Module Configuration Plug or Plugs, the second involves the setting of the Module Switches, and the third involves the setting of the Universal I/O Chassis backplane switches located on the left hand, lower side of the backplane as you look into the chassis. Note that there are two styles of Remote I/O Adapter, they are easily discerned by looking at SW 2. In the older style module SW 2 is a 4 position DIP switch, in the newer style, SW 2 is a 6 position DIP switch.
Setting the Module Configuration Plug(s)
If you have the older style Remote I/O Adapter begin by laying the module on its right side (label side down). Remove the left cover by removing the 4 screws. Locate the configuration plug and place the jumper in the right most position as indicated in figure 4.1 . Replace the cover and secure the 4 screws.
If you have the newer style Remote I/O Adapter, access to the Module Configuration Plugs can be gained through a small access hole in the lower left corner of the left cover of the module. Place all three jumpers in the left most position as indicated in figure 4.1.
In either of the above cases the Remote I/O Adapter module is placed in a mode for use with 32-point I/O modules and any address method. This is the configuration used in an EPICS control system. Note that in this mode you may not use the 1771-IX or the 1771-IY modules.
S1 is the Address Switch Assembly in both the newer and older style Remote I/O adapters. Switches 1 - 6 select the Universal I/O Chassis adapter number. Observe figure 4.2 for the proper address settings, when the switches are closed (ON) this corresponds to a binary 0 in the adapter address, and when the switches are open (OFF) this corresponds to a binary 1 in the adapter address. Note that switches 1 - 3 must always remain in their closed (ON) positions as the EPICS control system only uses adapter addresses 0 - 7.
Switches 7 and 8 should remain in the closed (ON) position as this will place the Remote I/O adapter in the 1st I/O group number 0, used in the EPICS control system.
S2 sets the baud rate and other configurations. For both the older and newer style of Remote I/O Adapter switch number 1 should be closed (ON), and switch number 2 should be open (OFF) this sets the baud rate at 57.6K baud and allows for a link distance of 10,000ft over twisted pair cable. This is the preferred setting for an EPICS control system. Switch number 3 should remain open (OFF) as it is not used, and switch number 4 should remain open (OFF) to put the Remote I/O adapter in scanning mode for all slots.
If you have the newer style Remote I/O Adapter switch number 5 should be open (OFF) for unrestricted emulation, and switch number 6 should be open (OFF) as it is not used. A summary of switch positions is available in figure 4.3.
Setting the Universal I/O Chassis backplane switches
The Allen-Bradley Universal I/O Chassis contains a backplane switch assembly located on the left hand, lower side of the backplane as you look into the chassis. The switches are labeled 1 - 8, with switch 1 on the top, and switch 8 on the bottom.
Switch 1 is the Last State Switch. When closed (ON) outputs from the chassis will remain in the last state when a fault is detected. When open (OFF) the outputs will be de-energized when a fault is detected. The common EPICS setting for this switch is closed (ON).
Switch 2 is the Processor Restart Switch. When closed (ON) the processor has the ability to restart the chassis. When open (OFF) the chassis must be restarted at the chassis. The common EPICS setting for this switch is closed (ON).
Switch 3 and Switch 4 are not used, and should always remain open (OFF).
Switch 5 and Switch 6 should always remain open (OFF) to select 2 slot addressing.
Switch 7 is not used, and should always remain open (OFF).
Switch 8 is the Last Chassis Switch. When closed (ON) the chassis is not the last chassis of a single ADAPTER number. When open (OFF) the chassis is the only chassis associated with a single ADAPTER number. The common EPICS setting for this switch is open (OFF).
1771-ASB Remote I/O Adapter Module Installation
The Allen-Bradley 1771-ASB Remote I/O Adapter Module may be installed in any Allen-Bradley Universal I/O Chassis, 1771-A1B, 1771-A2B, 1771-A3B, or 1771-A4B. Before Installation, calculate the power requirements of the modules currently in the chassis. Add to that 1.2A @ 5V DC, the current required by the 1771-ASB. Check to be sure that this combined current requirement does not exceed the current driving ability of the chassis power supply combination.
Module Location in the I/O Chassis
The 171-ASB must be placed in the extreme left slot of the Universal I/O Chassis. It is suggested that this module be placed away from AC modules or high voltage DC modules to minimize electrical noise interference.
The Allen Bradley Universal I/O chassis have the ability to limit the slot access to certain modules by the implementation of a keying system. Modules are slotted in two places at the edge of the circuit board. The position of the keying bands on the backplane connector of the I/O chassis must correspond to these slots. To key a slot for use by the 1771-ASB Remote I/O Adapter only (this would in the case of the 1771-ASB be the left most slot), place the keying bands between 54 and 56 and between 16 and 18 on the I/O chassis backplane connector.
Before a module is inserted into the Universal I/O Chassis, be sure that the power to the chassis is shut off. This can be done without shutting off the IOC that the Universal I/O Chassis is connected to. To insert the module, place it in the plastic tracks on the top and bottom of the Universal I/O Chassis. Slide the module into the Universal I/O Chassis until the module comes in contact with the backplane connector. Do not force the module in, instead apply firm and even pressure on the module to seat it properly on the backplane connector. Snap the chassis latch over the top of the module and connect the wiring arm to the module. The Universal I/O Chassis should begin communicating with the host IOC when power is reapplied, no rebooting of the IOC will have to be done.
1771-ASB Remote I/O Adapter Module Wiring Connection
Connection of analog signals to the 1771-ASB are accomplished through the use of the wiring arm. Signals should be connected to the screw terminals on the wiring arm, as detailed in figure 4.4, and the wiring arm should be connected to the front tab connector on the 1771-ASB. If the 1771-ASB is the last adapter on a link, or the only adapter on a link, be sure to add the I/O Channel terminator, Allen-Bradley Catalog # 1770-XT to the wiring arm.
1771-ASB Remote I/O Adapter Module Use
The front panel of the 1771-ASB contains a green ACTIVE, a red ADAPTER FAULT, and a red I/O RACK FAULT indicator. During normal operation the ACTIVE indicator should be illuminated, and the other two indicators should be out. The possible combinations of indicator actions are listed in figure 4.5.
