Functional description and allocation of terminal pins Manual BG41/BG42/BG43
3-34 Rev. 99/49
3.2.8.2 Cascading of counter 1 and 2 to a 32 bit counter
Counter 1 and 2 can be interconnected by the three jumpers X1, X2 and X3. The following settings
are possible:
Jumper X1, X2 and X3 in position 16
Standard position, both counters are operated independantly from each other.
Jumper X1, X2 and X3 in position 32
Counter 1 and 2 are cascaded by means of hardware. The inputs of counter 2 are not to be connected
and counter 2 is to be operated in mode 0. The 32 bit counter value can be obtained from the
counter value of counter 1 (low word) and the counter value of counter 2 (high word).
3.2.8.3 Carry and borrow handling
The counters provide borrow or carry information for each counter channel. Any carry or borrow
flag which appears is saved in the status register. The flags can be deleted by describing the counter
with a new value. A carry which is set is deleted by a borrow and vice-versa. The carry or borrow
flag can be alternatively placed on the yellow light emitting diodes on the front of the building
block and on the 25-pole SubD socket’s switch outputs. The choice is determined by means of the
jumper X4, X5 and X6:
•= Channel 1 over Jumper X6 CY1 (Carry Channel 1) or BW1 (Borrow Channel 1)
•= Channel 2 over Jumper X5 CY2 (Carry Channel 2) or BW2 (Borrow Channel 2)
•= Channel 3 over Jumper X4 CY3 (Carry Channel 3) or BW3 (Borrow Channel 3)
With the modules it is possible to connect 5V or 24V to the outputs. By active borrow or carry the
respective voltage is connected to the output. The output is non-floating and is not short-circuit
proof. It can drive a maximum of 200mA. Ensure to have a joint mass point.
The 5V module receives its voltage from the internal 5V. In the case of the 24V module, the 24V
voltage supply must be separately fed. This can occur over the rear cover bus or over the 25-pole
SubD socket.
One is to note, that in the case of external supply the rear cover bus is
disconnected by the plug connector J6. For further details see chapter 5.2.9.
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